make hotkey configuration more timing tolerant

src/ui/settings/Keybind.svelte

@@ -7,42 +7,49 @@
 
     const id = Math.random().toString().slice(2);
     const dispatch = createEventDispatcher();
-    const modifierKeys = new Set(['Alt', 'AltGraph', 'Control', 'Fn', 'FnLock', 'Meta', 'Shift', 'Super', ]);
+    const MODIFIERS = new Set(['Alt', 'AltGraph', 'Control', 'Fn', 'FnLock', 'Meta', 'Shift', 'Super', ]);
+
+
     let listening = false;
+    let keysPressed = [];
+
+    function addModifiers(event) {
+        // add modifier key if it isn't already present
+        if (MODIFIERS.has(event.key) && keysPressed.indexOf(event.key) === -1) {
+            keysPressed.push(event.key);
+        }
+    }
+
+    function addMainKey(event) {
+        if (!MODIFIERS.has(event.key)) {
+            keysPressed.push(event.key);
+            
+            value.keys = keysPressed.join('+');
+            dispatch('update', {value});
+            event.preventDefault();
+            event.stopPropagation();
+
+            unlisten();
+        }
+    }
     
     function listen() {
         // don't re-listen if we already are
         if (listening) return;
 
         listening = true;
-        window.addEventListener('keyup', setKeybind, {once: true});
+        window.addEventListener('keydown', addModifiers);
+        window.addEventListener('keyup', addMainKey);
         // setTimeout avoids reacting to the click event that we are currently processing
-        setTimeout(() => window.addEventListener('click', cancel, {once: true}), 0);
+        setTimeout(() => window.addEventListener('click', unlisten), 0);
     }
 
-    function setKeybind(event) {
-        // separate events fire for modifier keys, even when they are combined with a regular key
-        if (modifierKeys.has(event.key)) return;
-
-        let keys = [];
-        if (event.ctrlKey) keys.push('Ctrl');
-        if (event.altKey) keys.push('Alt');
-        if (event.metaKey) keys.push('Meta');
-        if (event.shiftKey) keys.push('Shift');
-        // capitalize
-        keys.push(event.key);
-
-        value.keys = keys.join('+');
-        dispatch('update', {value});
+    function unlisten() {
         listening = false;
-        window.removeEventListener('click', cancel, {once: true});
-        event.preventDefault();
-        event.stopPropagation();
-    }
-
-    function cancel() {
-        listening = false;
-        window.removeEventListener('keyup', setKeybind, {once: true});
+        keysPressed = [];
+        window.removeEventListener('keydown', addModifiers);
+        window.removeEventListener('keyup', addMainKey);
+        window.removeEventListener('click', unlisten);
     }
 </script>