diff --git a/src/App/App.tsx b/src/App/App.tsx
index 34a25bb..e9d23f6 100644
--- a/src/App/App.tsx
+++ b/src/App/App.tsx
@@ -71,7 +71,7 @@ function getPlantState<T>(plant: Plant<T>, trace: TraceItem[], idx: number): T |
 
 export function App() {
   const [insertMode, setInsertMode] = useState<InsertMode>("and");
-  const [historyState, setHistoryState] = useState<EditHistory>({current: emptyState, history: [], future: []});
+  const [editHistory, setEditHistory] = useState<EditHistory>({current: emptyState, history: [], future: []});
   const [trace, setTrace] = useState<TraceState|null>(null);
   const [time, setTime] = useState<TimeMode>({kind: "paused", simtime: 0});
   const [modal, setModal] = useState<ReactElement|null>(null);
@@ -82,10 +82,57 @@ export function App() {
 
   const plant = plants.find(([pn, p]) => pn === plantName)![1];
 
-  const editorState = historyState.current;
+  const editorState = editHistory.current;
   const setEditorState = useCallback((cb: (value: VisualEditorState) => VisualEditorState) => {
-    setHistoryState(historyState => ({...historyState, current: cb(historyState.current)}));
-  }, [setHistoryState]);
+    setEditHistory(historyState => ({...historyState, current: cb(historyState.current)}));
+  }, [setEditHistory]);
+
+  // recover editor state from URL - we need an effect here because decompression is asynchronous
+  useEffect(() => {
+    try {
+      const compressedState = window.location.hash.slice(1);
+      const ds = new DecompressionStream("deflate");
+      const writer = ds.writable.getWriter();
+      writer.write(Uint8Array.fromBase64(compressedState)).catch(e => {
+        console.error("could not recover state:", e);
+      });
+      writer.close().catch(e => {
+        console.error("could not recover state:", e);
+      });
+      new Response(ds.readable).arrayBuffer().then(decompressedBuffer => {
+        try {
+          const recoveredState = JSON.parse(new TextDecoder().decode(decompressedBuffer));
+          setEditorState(() => recoveredState);
+        }
+        catch (e) {
+        console.error("could not recover state:", e);
+      }
+      }).catch(e => {
+        console.error("could not recover state:", e);
+      });
+    }
+    catch (e) {
+      console.error("could not recover state:", e);
+    }
+  }, []);
+
+  // save editor state in URL
+  useEffect(() => {
+    const timeout = setTimeout(() => {
+      const serializedState = JSON.stringify(editorState);
+      const stateBuffer = new TextEncoder().encode(serializedState);
+      const cs = new CompressionStream("deflate");
+      const writer = cs.writable.getWriter();
+      writer.write(stateBuffer);
+      writer.close();
+      // todo: cancel this promise handler when concurrently starting another compression job
+      new Response(cs.readable).arrayBuffer().then(compressedStateBuffer => {
+        const compressedStateString = new Uint8Array(compressedStateBuffer).toBase64();
+        window.location.hash = "#"+compressedStateString;
+      });
+    }, 100);
+    return () => clearTimeout(timeout);
+  }, [editorState]);
 
   const refRightSideBar = useRef<HTMLDivElement>(null);
 
@@ -93,16 +140,18 @@ export function App() {
   const conns = useMemo(() => detectConnections(editorState), [editorState]);
   const [ast, syntaxErrors] = useMemo(() => parseStatechart(editorState, conns), [editorState, conns]);
 
+  console.log('render App', ast);
+
   // append editor state to undo history
   const makeCheckPoint = useCallback(() => {
-    setHistoryState(historyState => ({
+    setEditHistory(historyState => ({
       ...historyState,
       history: [...historyState.history, historyState.current],
       future: [],
     }));
-  }, [setHistoryState]);
+  }, [setEditHistory]);
   const onUndo = useCallback(() => {
-    setHistoryState(historyState => {
+    setEditHistory(historyState => {
       if (historyState.history.length === 0) {
         return historyState; // no change
       }
@@ -112,9 +161,9 @@ export function App() {
         future: [...historyState.future, historyState.current],
       }
     })
-  }, [setHistoryState]);
+  }, [setEditHistory]);
   const onRedo = useCallback(() => {
-    setHistoryState(historyState => {
+    setEditHistory(historyState => {
       if (historyState.future.length === 0) {
         return historyState; // no change
       }
@@ -124,9 +173,19 @@ export function App() {
         future: historyState.future.slice(0,-1),
       }
     });
-  }, [setHistoryState]);
-  
-  function onInit() {
+  }, [setEditHistory]);
+
+  const scrollDownSidebar = useCallback(() => {
+    if (refRightSideBar.current) {
+      const el = refRightSideBar.current;
+      // hack: we want to scroll to the new element, but we have to wait until it is rendered...
+      setTimeout(() => {
+        el.scrollIntoView({block: "end", behavior: "smooth"});
+      }, 50);
+    }
+  }, [refRightSideBar.current]);
+
+  const onInit = useCallback(() => {
     const timestampedEvent = {simtime: 0, inputEvent: "<init>"};
     let config;
     try {
@@ -145,7 +204,8 @@ export function App() {
     }
     setTime({kind: "paused", simtime: 0});
     scrollDownSidebar();
-  }
+  }, [ast, scrollDownSidebar, setTime, setTrace]);
+
   const onClear = useCallback(() => {
     setTrace(null);
     setTime({kind: "paused", simtime: 0});
@@ -245,16 +305,6 @@ export function App() {
     }
   }
 
-  const scrollDownSidebar = useCallback(() => {
-    if (refRightSideBar.current) {
-      const el = refRightSideBar.current;
-      // hack: we want to scroll to the new element, but we have to wait until it is rendered...
-      setTimeout(() => {
-        el.scrollIntoView({block: "end", behavior: "smooth"});
-      }, 50);
-    }
-  }, []);
-
   useEffect(() => {
     console.log("Welcome to StateBuddy!");
     () => {
@@ -324,7 +374,7 @@ export function App() {
             }}
           >
             <TopPanel
-              {...{trace, ast, time, setTime, onUndo, onRedo, onInit, onClear, onRaise, onBack, insertMode, setInsertMode, setModal, zoom, setZoom, showKeys, setShowKeys, history: historyState}}
+              {...{trace, time, setTime, onUndo, onRedo, onInit, onClear, onBack, insertMode, setInsertMode, setModal, zoom, setZoom, showKeys, setShowKeys, editHistory}}
             />
           </Box>
           {/* Below the top bar: Editor */}
diff --git a/src/App/TopPanel.tsx b/src/App/TopPanel.tsx
index 415e9f6..c3bcdf6 100644
--- a/src/App/TopPanel.tsx
+++ b/src/App/TopPanel.tsx
@@ -1,27 +1,23 @@
-import { Dispatch, memo, ReactElement, SetStateAction, useEffect, useState } from "react";
-import { BigStep, TimerElapseEvent, Timers } from "../statecharts/runtime_types";
+import { Dispatch, memo, ReactElement, SetStateAction, useCallback, useEffect, useState } from "react";
+import { TimerElapseEvent, Timers } from "../statecharts/runtime_types";
 import { getSimTime, setPaused, setRealtime, TimeMode } from "../statecharts/time";
-import { Statechart } from "../statecharts/abstract_syntax";
+import { InsertMode } from "../VisualEditor/VisualEditor";
+import { About } from "./About";
+import { EditHistory, TraceState } from "./App";
+import { KeyInfoHidden, KeyInfoVisible } from "./KeyInfo";
+import { UndoRedoButtons } from "./TopPanel/UndoRedoButtons";
+import { ZoomButtons } from "./TopPanel/ZoomButtons";
+import { formatTime } from "./util";
 
-import CachedIcon from '@mui/icons-material/Cached';
-import PauseIcon from '@mui/icons-material/Pause';
-import PlayArrowIcon from '@mui/icons-material/PlayArrow';
-import BoltIcon from '@mui/icons-material/Bolt';
-import SkipNextIcon from '@mui/icons-material/SkipNext';
-import SkipPreviousIcon from '@mui/icons-material/SkipPrevious';import TrendingFlatIcon from '@mui/icons-material/TrendingFlat';
 import AccessAlarmIcon from '@mui/icons-material/AccessAlarm';
-import StopIcon from '@mui/icons-material/Stop';
+import CachedIcon from '@mui/icons-material/Cached';
 import InfoOutlineIcon from '@mui/icons-material/InfoOutline';
 import KeyboardIcon from '@mui/icons-material/Keyboard';
-
-import { formatTime } from "./util";
-import { InsertMode } from "../VisualEditor/VisualEditor";
-import { KeyInfoHidden, KeyInfoVisible } from "./KeyInfo";
-import { About } from "./About";
-import { RountangleIcon, PseudoStateIcon, HistoryIcon } from "./Icons";
-import { EditHistory, TraceState } from "./App";
-import { ZoomButtons } from "./TopPanel/ZoomButtons";
-import { UndoRedoButtons } from "./TopPanel/UndoRedoButtons";
+import PauseIcon from '@mui/icons-material/Pause';
+import PlayArrowIcon from '@mui/icons-material/PlayArrow';
+import SkipNextIcon from '@mui/icons-material/SkipNext';
+import StopIcon from '@mui/icons-material/Stop';
+import { InsertModes } from "./TopPanel/InsertModes";
 
 export type TopPanelProps = {
   trace: TraceState | null,
@@ -31,9 +27,7 @@ export type TopPanelProps = {
   onRedo: () => void,
   onInit: () => void,
   onClear: () => void,
-  // onRaise: (e: string, p: any) => void,
   onBack: () => void,
-  // ast: Statechart,
   insertMode: InsertMode,
   setInsertMode: Dispatch<SetStateAction<InsertMode>>,
   setModal: Dispatch<SetStateAction<ReactElement|null>>,
@@ -41,22 +35,12 @@ export type TopPanelProps = {
   setZoom: Dispatch<SetStateAction<number>>,
   showKeys: boolean,
   setShowKeys: Dispatch<SetStateAction<boolean>>,
-  history: EditHistory,
+  editHistory: EditHistory,
 }
 
 const ShortCutShowKeys = <kbd>~</kbd>;
 
-const insertModes: [InsertMode, string, ReactElement, ReactElement][] = [
-  ["and", "AND-states", <RountangleIcon kind="and"/>, <kbd>A</kbd>],
-  ["or", "OR-states", <RountangleIcon kind="or"/>, <kbd>O</kbd>],
-  ["pseudo", "pseudo-states", <PseudoStateIcon/>, <kbd>P</kbd>],
-  ["shallow", "shallow history", <HistoryIcon kind="shallow"/>, <kbd>H</kbd>],
-  ["deep", "deep history", <HistoryIcon kind="deep"/>, <></>],
-  ["transition", "transitions", <TrendingFlatIcon fontSize="small"/>, <kbd>T</kbd>],
-  ["text", "text", <>&nbsp;T&nbsp;</>, <kbd>X</kbd>],
-];
-
-export const TopPanel = memo(function TopPanel({trace, time, setTime, onUndo, onRedo, onInit, onClear, onBack, insertMode, setInsertMode, setModal, zoom, setZoom, showKeys, setShowKeys, history}: TopPanelProps) {
+export const TopPanel = memo(function TopPanel({trace, time, setTime, onUndo, onRedo, onInit, onClear, onBack, insertMode, setInsertMode, setModal, zoom, setZoom, showKeys, setShowKeys, editHistory}: TopPanelProps) {
   const [displayTime, setDisplayTime] = useState("0.000");
   const [timescale, setTimescale] = useState(1);
 
@@ -64,6 +48,77 @@ export const TopPanel = memo(function TopPanel({trace, time, setTime, onUndo, on
 
   const KeyInfo = showKeys ? KeyInfoVisible : KeyInfoHidden;
 
+  const updateDisplayedTime = useCallback(() => {
+    const now = Math.round(performance.now());
+    const timeMs = getSimTime(time, now);
+    setDisplayTime(formatTime(timeMs));
+  }, [time, setDisplayTime]);
+
+  useEffect(() => {
+    // This has no effect on statechart execution. In between events, the statechart is doing nothing. However, by updating the displayed time, we give the illusion of continuous progress.
+    const interval = setInterval(() => {
+      updateDisplayedTime();
+    }, 43); // every X ms -> we want a value that makes the numbers 'dance' while not using too much CPU
+    return () => {
+      clearInterval(interval);
+    }
+  }, [time, updateDisplayedTime]);
+
+  const onChangePaused = useCallback((paused: boolean, wallclktime: number) => {
+    setTime(time => {
+      if (paused) {
+        return setPaused(time, wallclktime);
+      }
+      else {
+        return setRealtime(time, timescale, wallclktime);
+      }
+    });
+    updateDisplayedTime();
+  }, [setTime, updateDisplayedTime]);
+
+  const onTimeScaleChange = useCallback((newValue: string, wallclktime: number) => {
+    const asFloat = parseFloat(newValue);
+    if (Number.isNaN(asFloat)) {
+      return;
+    }
+    const maxed = Math.min(asFloat, 64);
+    const mined = Math.max(maxed, 1/64);
+    setTimescale(mined);
+    setTime(time => {
+      if (time.kind === "paused") {
+        return time;
+      }
+      else {
+        return setRealtime(time, mined, wallclktime);
+      }
+    });
+  }, [setTime, setTimescale]);
+
+  // timestamp of next timed transition, in simulated time
+  const timers: Timers = config?.kind === "bigstep" && config.environment.get("_timers") || [];
+  const nextTimedTransition: [number, TimerElapseEvent] | undefined = timers[0];
+
+  const onSkip = useCallback(() => {
+    const now = Math.round(performance.now());
+    if (nextTimedTransition) {
+      setTime(time => {
+        if (time.kind === "paused") {
+          return {kind: "paused", simtime: nextTimedTransition[0]};
+        }
+        else {
+          return {kind: "realtime", scale: time.scale, since: {simtime: nextTimedTransition[0], wallclktime: now}};
+        }
+      });
+    }
+  }, [nextTimedTransition, setTime]);
+
+  const onSlower = useCallback(() => {
+    onTimeScaleChange((timescale/2).toString(), Math.round(performance.now()));
+  }, [onTimeScaleChange]);
+  const onFaster = useCallback(() => {
+    onTimeScaleChange((timescale*2).toString(), Math.round(performance.now()));
+  }, [onTimeScaleChange, timescale]);
+
   useEffect(() => {
     const onKeyDown = (e: KeyboardEvent) => {
       if (!e.ctrlKey) {
@@ -123,86 +178,13 @@ export const TopPanel = memo(function TopPanel({trace, time, setTime, onUndo, on
     return () => {
       window.removeEventListener("keydown", onKeyDown);
     };
-  }, [time, onInit, timescale]);
-
-  function updateDisplayedTime() {
-    const now = Math.round(performance.now());
-    const timeMs = getSimTime(time, now);
-    setDisplayTime(formatTime(timeMs));
-  }
-
-  useEffect(() => {
-    // This has no effect on statechart execution. In between events, the statechart is doing nothing. However, by updating the displayed time, we give the illusion of continuous progress.
-    const interval = setInterval(() => {
-      updateDisplayedTime();
-    }, 43); // every X ms -> we want a value that makes the numbers 'dance' while not using too much CPU
-    return () => {
-      clearInterval(interval);
-    }
-  }, [time]);
-
-
-  function onChangePaused(paused: boolean, wallclktime: number) {
-    setTime(time => {
-      if (paused) {
-        return setPaused(time, wallclktime);
-      }
-      else {
-        return setRealtime(time, timescale, wallclktime);
-      }
-    });
-    updateDisplayedTime();
-  }
-
-  function onTimeScaleChange(newValue: string, wallclktime: number) {
-    const asFloat = parseFloat(newValue);
-    if (Number.isNaN(asFloat)) {
-      return;
-    }
-    const maxed = Math.min(asFloat, 64);
-    const mined = Math.max(maxed, 1/64);
-    setTimescale(mined);
-    setTime(time => {
-      if (time.kind === "paused") {
-        return time;
-      }
-      else {
-        return setRealtime(time, mined, wallclktime);
-      }
-    });
-  }
-
-  // timestamp of next timed transition, in simulated time
-  const timers: Timers = config?.kind === "bigstep" && config.environment.get("_timers") || [];
-  const nextTimedTransition: [number, TimerElapseEvent] | undefined = timers[0];
-
-  function onSkip() {
-    const now = Math.round(performance.now());
-    if (nextTimedTransition) {
-      setTime(time => {
-        if (time.kind === "paused") {
-          return {kind: "paused", simtime: nextTimedTransition[0]};
-        }
-        else {
-          return {kind: "realtime", scale: time.scale, since: {simtime: nextTimedTransition[0], wallclktime: now}};
-        }
-      });
-    }
-  }
-
-  function onSlower() {
-    onTimeScaleChange((timescale/2).toString(), Math.round(performance.now()));
-  }
-  function onFaster() {
-    onTimeScaleChange((timescale*2).toString(), Math.round(performance.now()));
-  }
+  }, [trace, config, time, onInit, timescale, onChangePaused, setShowKeys, onUndo, onRedo, onSlower, onFaster, onSkip, onBack, onClear]);
 
   return <div className="toolbar">
-
     {/* shortcuts / about */}
     <div className="toolbarGroup">
       <KeyInfo keyInfo={ShortCutShowKeys}>
-        <button title="show/hide keyboard shortcuts" className={showKeys?"active":""} onClick={() => setShowKeys(s => !s)}><KeyboardIcon fontSize="small"/></button>
+        <button title="show/hide keyboard shortcuts" className={showKeys?"active":""} onClick={useCallback(() => setShowKeys(s => !s), [setShowKeys])}><KeyboardIcon fontSize="small"/></button>
       </KeyInfo>
       <button title="about StateBuddy" onClick={() => setModal(<About setModal={setModal}/>)}><InfoOutlineIcon fontSize="small"/></button>
       &emsp;
@@ -216,28 +198,21 @@ export const TopPanel = memo(function TopPanel({trace, time, setTime, onUndo, on
 
     {/* undo / redo */}
     <div className="toolbarGroup">
-      <UndoRedoButtons showKeys={showKeys} onUndo={onUndo} onRedo={onRedo} historyLength={history.history.length} futureLength={history.future.length}/>
+      <UndoRedoButtons showKeys={showKeys} onUndo={onUndo} onRedo={onRedo} historyLength={editHistory.history.length} futureLength={editHistory.future.length}/>
       &emsp;
     </div>
 
     {/* insert rountangle / arrow / ... */}
     <div className="toolbarGroup">
-      {insertModes.map(([m, hint, buttonTxt, keyInfo]) =>
-        <KeyInfo key={m} keyInfo={keyInfo}>
-        <button
-          title={"insert "+hint}
-          disabled={insertMode===m}
-          className={insertMode===m ? "active":""}
-          onClick={() => setInsertMode(m)}
-        >{buttonTxt}</button></KeyInfo>)}
+      <InsertModes insertMode={insertMode} setInsertMode={setInsertMode} showKeys={showKeys}/>
       &emsp;
     </div>
 
     {/* execution */}
     <div className="toolbarGroup">
 
-      {/* init / clear / pause / real time */}
       <div className="toolbarGroup">
+        {/* init / clear */}
         <KeyInfo keyInfo={<kbd>I</kbd>}>
           <button title="(re)initialize simulation" onClick={onInit} ><PlayArrowIcon fontSize="small"/><CachedIcon fontSize="small"/></button>
         </KeyInfo>
@@ -245,6 +220,7 @@ export const TopPanel = memo(function TopPanel({trace, time, setTime, onUndo, on
           <button title="clear the simulation" onClick={onClear} disabled={!config}><StopIcon fontSize="small"/></button>
         </KeyInfo>
         &emsp;
+        {/* pause / real time */}
         <KeyInfo keyInfo={<><kbd>Space</kbd> toggles</>}>
           <button title="pause the simulation" disabled={!config || time.kind==="paused"} className={(config && time.kind==="paused") ? "active":""} onClick={() => onChangePaused(true, Math.round(performance.now()))}><PauseIcon fontSize="small"/></button>
           <button title="run the simulation in real time" disabled={!config || time.kind==="realtime"} className={(config && time.kind==="realtime") ? "active":""} onClick={() => onChangePaused(false, Math.round(performance.now()))}><PlayArrowIcon fontSize="small"/></button>
@@ -282,44 +258,5 @@ export const TopPanel = memo(function TopPanel({trace, time, setTime, onUndo, on
         </div>
       </div>
     </div>
-
-    {/* input events */}
-    {/* <div className="toolbarGroup">
-      {ast.inputEvents &&
-        <>
-          {ast.inputEvents.map(({event, paramName}) =>
-            <div key={event+'/'+paramName} className="toolbarGroup">
-              <button
-                className="inputEvent"
-                title={`raise this input event`}
-                disabled={!rt}
-                onClick={() => {
-                  // @ts-ignore
-                  const param = document.getElementById(`input-${event}-param`)?.value;
-                  let paramParsed;
-                  try {
-                    if (param) {
-                      paramParsed = JSON.parse(param); // may throw
-                    }
-                  }
-                  catch (e) {
-                    alert("invalid json");
-                    return;
-                  }
-                  onRaise(event, paramParsed);
-                }}>
-                <BoltIcon fontSize="small"/>
-                {event}
-              </button>
-              {paramName &&
-                <><input id={`input-${event}-param`} style={{width: 20}} placeholder={paramName}/></>
-              }
-              &nbsp;
-            </div>
-          )}
-        </>
-      }
-    </div> */}
-
   </div>;
 });
diff --git a/src/App/TopPanel/InsertModes.tsx b/src/App/TopPanel/InsertModes.tsx
new file mode 100644
index 0000000..61d0953
--- /dev/null
+++ b/src/App/TopPanel/InsertModes.tsx
@@ -0,0 +1,28 @@
+import { Dispatch, memo, ReactElement, SetStateAction } from "react";
+import { KeyInfoHidden, KeyInfoVisible } from "../KeyInfo";
+import { InsertMode } from "@/VisualEditor/VisualEditor";
+import { HistoryIcon, PseudoStateIcon, RountangleIcon } from "../Icons";
+
+import TrendingFlatIcon from '@mui/icons-material/TrendingFlat';
+
+const insertModes: [InsertMode, string, ReactElement, ReactElement][] = [
+  ["and", "AND-states", <RountangleIcon kind="and"/>, <kbd>A</kbd>],
+  ["or", "OR-states", <RountangleIcon kind="or"/>, <kbd>O</kbd>],
+  ["pseudo", "pseudo-states", <PseudoStateIcon/>, <kbd>P</kbd>],
+  ["shallow", "shallow history", <HistoryIcon kind="shallow"/>, <kbd>H</kbd>],
+  ["deep", "deep history", <HistoryIcon kind="deep"/>, <></>],
+  ["transition", "transitions", <TrendingFlatIcon fontSize="small"/>, <kbd>T</kbd>],
+  ["text", "text", <>&nbsp;T&nbsp;</>, <kbd>X</kbd>],
+];
+
+export const InsertModes = memo(function InsertModes({showKeys, insertMode, setInsertMode}: {showKeys: boolean, insertMode: InsertMode, setInsertMode: Dispatch<SetStateAction<InsertMode>>}) {
+  const KeyInfo = showKeys ? KeyInfoVisible : KeyInfoHidden;
+  return <>{insertModes.map(([m, hint, buttonTxt, keyInfo]) => <KeyInfo key={m} keyInfo={keyInfo}>
+    <button
+      title={"insert "+hint}
+      disabled={insertMode===m}
+      className={insertMode===m ? "active":""}
+      onClick={() => setInsertMode(m)}
+    >{buttonTxt}</button>
+  </KeyInfo>)}</>;
+})
\ No newline at end of file
diff --git a/src/VisualEditor/VisualEditor.tsx b/src/VisualEditor/VisualEditor.tsx
index f70ae2e..654a0f8 100644
--- a/src/VisualEditor/VisualEditor.tsx
+++ b/src/VisualEditor/VisualEditor.tsx
@@ -81,45 +81,15 @@ export const VisualEditor = memo(function VisualEditor({state, setState, trace,
   const [dragging, setDragging] = useState(false);
 
   // uid's of selected rountangles
-  // const [selection, setSelection] = useState<Selection>([]);
   const selection = state.selection || [];
-  const setSelection = (cb: (oldSelection: Selection) => Selection) =>
-    setState(oldState => ({...oldState, selection: cb(oldState.selection)}));
+  const setSelection = useCallback((cb: (oldSelection: Selection) => Selection) =>
+    setState(oldState => ({...oldState, selection: cb(oldState.selection)})),[setState]);
 
   // not null while the user is making a selection
   const [selectingState, setSelectingState] = useState<SelectingState>(null);
 
   const refSVG = useRef<SVGSVGElement>(null);
 
-  useEffect(() => {
-    try {
-      const compressedState = window.location.hash.slice(1);
-      const ds = new DecompressionStream("deflate");
-      const writer = ds.writable.getWriter();
-      writer.write(Uint8Array.fromBase64(compressedState)).catch(e => {
-        console.error("could not recover state:", e);
-      });
-      writer.close().catch(e => {
-        console.error("could not recover state:", e);
-      });
-
-      new Response(ds.readable).arrayBuffer().then(decompressedBuffer => {
-        try {
-          const recoveredState = JSON.parse(new TextDecoder().decode(decompressedBuffer));
-          setState(() => recoveredState);
-        }
-        catch (e) {
-        console.error("could not recover state:", e);
-      }
-      }).catch(e => {
-        console.error("could not recover state:", e);
-      });
-    }
-    catch (e) {
-      console.error("could not recover state:", e);
-    }
-  }, []);
-
   useEffect(() => {
     // bit of a hacky way to force the animation on fired transitions to replay, if the new 'rt' contains the same fired transitions as the previous one
     requestAnimationFrame(() => {
@@ -134,25 +104,6 @@ export const VisualEditor = memo(function VisualEditor({state, setState, trace,
     })
   }, [trace && trace.idx]);
 
-  useEffect(() => {
-    const timeout = setTimeout(() => {
-      const serializedState = JSON.stringify(state);
-      const stateBuffer = new TextEncoder().encode(serializedState);
-
-      const cs = new CompressionStream("deflate");
-      const writer = cs.writable.getWriter();
-      writer.write(stateBuffer);
-      writer.close();
-
-      // todo: cancel this promise handler when concurrently starting another compression job
-      new Response(cs.readable).arrayBuffer().then(compressedStateBuffer => {
-        const compressedStateString = new Uint8Array(compressedStateBuffer).toBase64();
-        window.location.hash = "#"+compressedStateString;
-      });
-    }, 100);
-    return () => clearTimeout(timeout);
-  }, [state]);
-
   const getCurrentPointer = useCallback((e: {pageX: number, pageY: number}) => {
     const bbox = refSVG.current!.getBoundingClientRect();
     return {
@@ -417,7 +368,7 @@ export const VisualEditor = memo(function VisualEditor({state, setState, trace,
     setSelectingState(null); // no longer making a selection
   }, [dragging, selectingState, refSVG.current]);
 
-  function deleteSelection() {
+  const deleteSelection = useCallback(() => {
     setState(state => ({
       ...state,
       rountangles: state.rountangles.filter(r => !state.selection.some(rs => rs.uid === r.uid)),
@@ -427,9 +378,9 @@ export const VisualEditor = memo(function VisualEditor({state, setState, trace,
       texts: state.texts.filter(t => !state.selection.some(ts => ts.uid === t.uid)),
       selection: [],
     }));
-  }
+  }, [setState]);
 
-  const onKeyDown = (e: KeyboardEvent) => {
+  const onKeyDown = useCallback((e: KeyboardEvent) => {
     if (e.key === "Delete") {
       // delete selection
       makeCheckPoint();
@@ -475,7 +426,7 @@ export const VisualEditor = memo(function VisualEditor({state, setState, trace,
         }))
       }
     }
-  };
+  }, [makeCheckPoint, deleteSelection, setState, setDragging]);
 
   useEffect(() => {
     // mousemove and mouseup are global event handlers so they keep working when pointer is outside of browser window
@@ -535,7 +486,7 @@ export const VisualEditor = memo(function VisualEditor({state, setState, trace,
     }
   }
 
-  function onPaste(e: ClipboardEvent) {
+  const onPaste = useCallback((e: ClipboardEvent) => {
     const data = e.clipboardData?.getData("text/plain");
     if (data) {
       let parsed;
@@ -547,8 +498,8 @@ export const VisualEditor = memo(function VisualEditor({state, setState, trace,
       }
       // const offset = {x: 40, y: 40};
       const offset = {x: 0, y: 0};
-      let nextID = state.nextID;
-      try {
+      setState(state => {
+        let nextID = state.nextID;
         const copiedRountangles: Rountangle[] = parsed.rountangles.map((r: Rountangle) => ({
           ...r,
           uid: (nextID++).toString(),
@@ -583,7 +534,7 @@ export const VisualEditor = memo(function VisualEditor({state, setState, trace,
           ...copiedTexts.map(t => ({uid: t.uid, parts: ["text"]})),
           ...copiedHistories.map(h => ({uid: h.uid, parts: ["history"]})),
         ];
-        setState(state => ({
+        return {
           ...state,
           rountangles: [...state.rountangles, ...copiedRountangles],
           diamonds: [...state.diamonds, ...copiedDiamonds],
@@ -592,16 +543,14 @@ export const VisualEditor = memo(function VisualEditor({state, setState, trace,
           history: [...state.history, ...copiedHistories],
           nextID: nextID,
           selection: newSelection,
-        }));
-        // copyInternal(newSelection, e); // doesn't work
-        e.preventDefault();
-      }
-      catch (e) {
-      }
+        };
+      });
+      // copyInternal(newSelection, e); // doesn't work
+      e.preventDefault();
     }
-  }
+  }, [setState]);
 
-  function copyInternal(selection: Selection, e: ClipboardEvent) {
+  const copyInternal = useCallback((state: VisualEditorState, selection: Selection, e: ClipboardEvent) => {
     const uidsToCopy = new Set(selection.map(shape => shape.uid));
     const rountanglesToCopy = state.rountangles.filter(r => uidsToCopy.has(r.uid));
     const diamondsToCopy = state.diamonds.filter(d => uidsToCopy.has(d.uid));
@@ -615,22 +564,22 @@ export const VisualEditor = memo(function VisualEditor({state, setState, trace,
       arrows: arrowsToCopy,
       texts: textsToCopy,
     }));
-  }
+  }, []);
 
-  function onCopy(e: ClipboardEvent) {
+  const onCopy = useCallback((e: ClipboardEvent) => {
     if (selection.length > 0) {
       e.preventDefault();
-      copyInternal(selection, e);
+      copyInternal(state, selection, e);
     }
-  }
+  }, [state, selection]);
 
-  function onCut(e: ClipboardEvent) {
+  const onCut = useCallback((e: ClipboardEvent) => {
     if (selection.length > 0) {
-      copyInternal(selection, e);
+      copyInternal(state, selection, e);
       deleteSelection();
       e.preventDefault();
     }
-  }
+  }, [state, selection]);
 
   const onEditText = useCallback((text: Text, newText: string) => {
     if (newText === "") {