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Throttle FG-window polling to fix race with shell hotkeys (fixes #166) #201

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Throttle FG-window polling to fix race with shell hotkeys (fixes #166) #201

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23 changes: 20 additions & 3 deletions Source/App/App.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -289,6 +289,14 @@ public void MonitorFGWindowName() {
}

private void _MonitorFGWindowName() {
// Bug fix: 20ms polling caused a race with the Windows shell during
// Win+Ctrl+Arrow desktop transitions (synchronous GetWindowText calls
// hammered the foreground window's message pump 50 times per second,
// intermittently swallowing the shell's own hotkey handling).
// Poll rate is now driven by whether anything actually needs sub-second
// foreground-name resolution. The history feeds:
// (a) feature.restorePreviousWindowFocus (default false) — needs ~200ms
// (b) tray-click "is Task View already open" heuristic — 1s is fine
while(true) {
try {
var fgWindowName = Util.OS.GetForegroundWindowName();
Expand All @@ -300,7 +308,8 @@ private void _MonitorFGWindowName() {
if(LastForegroundhWnd == IntPtr.Zero) {
LastForegroundhWnd = Util.OS.GetFolderViewHandle();
}
System.Threading.Thread.Sleep(20);
var pollIntervalMs = Settings.GetBool("feature.restorePreviousWindowFocus") ? 200 : 1000;
System.Threading.Thread.Sleep(pollIntervalMs);
} catch(Exception e) {
Util.Logging.WriteLine("App: Error: MonitorFGWindowName: " + e.Message);
System.Threading.Thread.Sleep(1000);
Expand All @@ -315,10 +324,18 @@ public void MonitorFocusedWindow() {
}

private void _monitorFocusedWindow() {
// Bug fix: this thread only exists to support feature.restorePreviousWindowFocus.
// When that feature is disabled (default), polling here is pure waste and
// contributes to the same desktop-switch race as _MonitorFGWindowName.
// Idle out at 5s when the feature is off; keep 200ms when it's on.
while(true) {
try {
_storeLastWinFocused();
System.Threading.Thread.Sleep(200);
if(Settings.GetBool("feature.restorePreviousWindowFocus")) {
_storeLastWinFocused();
System.Threading.Thread.Sleep(200);
} else {
System.Threading.Thread.Sleep(5000);
}
} catch(Exception e) {
Util.Logging.WriteLine("App: Error: _monitorFocusedWindow: " + e.Message);
System.Threading.Thread.Sleep(1000);
Expand Down