Windows' Auto-Hide Taskbar Feature Not Working with Custom Title Bar when Window is Maximized about window_manager

[damywise]

I had this exact issue except for the top bar.
Basically when the window is maximized, it doesn't leave any gap for the taskbar side.
Here's how I fixed it (should've opened a new PR for that) 81b972a (#374)
If you got time, maybe open a PR and try to experiment with the bottom border.

Don't do that, see below

[roman-yepishev]

The sample code from Microsoft at https://learn.microsoft.com/en-us/windows/apps/develop/title-bar#full-customization-example also exhibits this problem: microsoft/microsoft-ui-xaml#8431.

The workaround mentioned in that bug is using https://learn.microsoft.com/en-us/windows/win32/api/shobjidl_core/nf-shobjidl_core-itaskbarlist2-markfullscreenwindow#remarks:

Since Windows 7, call SetProp(hwnd, L”NonRudeHWND”, reinterpret_cast<HANDLE>(TRUE)) before showing a window to indicate to the Shell that the window should not be treated as full-screen. This ensures the taskbar does not adjust itself to be below the window in z-order.

[roman-yepishev]

Adding a call of SetProp with NonRudeHWND in windows/window_manager.cpp fixes the taskbar visibility:

diff --git a/windows/window_manager.cpp b/windows/window_manager.cpp
index 3484176..5bd0e28 100644
--- a/windows/window_manager.cpp
+++ b/windows/window_manager.cpp
@@ -256,6 +256,7 @@ bool WindowManager::IsFocused() {

 void WindowManager::Show() {
   HWND hWnd = GetMainWindow();
+  SetProp(hWnd, L"NonRudeHWND", reinterpret_cast<HANDLE>(TRUE));
   DWORD gwlStyle = GetWindowLong(hWnd, GWL_STYLE);
   gwlStyle = gwlStyle | WS_VISIBLE;
   if ((gwlStyle & WS_VISIBLE) == 0) {

However, since this is the first time I see the codebase, I am not sure where this call should actually live.

[damywise]

@roman-yepishev If this is only called once ever, you can put that here

window_manager/windows/window_manager.cpp

Lines 208 to 211 in ef786b1

	void WindowManager::WaitUntilReadyToShow() {
	::CoCreateInstance(CLSID_TaskbarList, NULL, CLSCTX_INPROC_SERVER,
	IID_PPV_ARGS(&taskbar_));
	}

and if you want, also enable/disable it when going to/from fullscreen here

window_manager/windows/window_manager.cpp

Lines 572 to 617 in ef786b1

	if (isFullScreen) { // Set to fullscreen
	::SendMessage(mainWindow, WM_SYSCOMMAND, SC_MAXIMIZE, 0);
	if (!is_frameless_) {
	auto monitor = MONITORINFO{};
	auto placement = WINDOWPLACEMENT{};
	monitor.cbSize = sizeof(MONITORINFO);
	placement.length = sizeof(WINDOWPLACEMENT);
	::GetWindowPlacement(mainWindow, &placement);
	::GetMonitorInfo(
	::MonitorFromWindow(mainWindow, MONITOR_DEFAULTTONEAREST), &monitor);
	::SetWindowLongPtr(mainWindow, GWL_STYLE,
	g_style_before_fullscreen & ~WS_OVERLAPPEDWINDOW);
	::SetWindowPos(mainWindow, HWND_TOP, monitor.rcMonitor.left,
	monitor.rcMonitor.top,
	monitor.rcMonitor.right - monitor.rcMonitor.left,
	monitor.rcMonitor.bottom - monitor.rcMonitor.top,
	SWP_NOOWNERZORDER | SWP_FRAMECHANGED);
	}
	} else { // Restore from fullscreen
	if (!g_maximized_before_fullscreen)
	Restore();
	::SetWindowLongPtr(mainWindow, GWL_STYLE,
	g_style_before_fullscreen | WS_OVERLAPPEDWINDOW);
	if (::IsZoomed(mainWindow)) {
	// Refresh the parent mainWindow.
	::SetWindowPos(mainWindow, nullptr, 0, 0, 0, 0,
	SWP_NOACTIVATE | SWP_NOMOVE | SWP_NOSIZE | SWP_NOZORDER |
	SWP_FRAMECHANGED);
	auto rect = RECT{};
	::GetClientRect(mainWindow, &rect);
	auto flutter_view = ::FindWindowEx(mainWindow, nullptr,
	kFlutterViewWindowClassName, nullptr);
	::SetWindowPos(flutter_view, nullptr, rect.left, rect.top,
	rect.right - rect.left, rect.bottom - rect.top,
	SWP_NOACTIVATE | SWP_NOZORDER);
	if (g_maximized_before_fullscreen)
	PostMessage(mainWindow, WM_SYSCOMMAND, SC_MAXIMIZE, 0);
	} else {
	::SetWindowPos(
	mainWindow, nullptr, g_frame_before_fullscreen.left,
	g_frame_before_fullscreen.top,
	g_frame_before_fullscreen.right - g_frame_before_fullscreen.left,
	g_frame_before_fullscreen.bottom - g_frame_before_fullscreen.top,
	SWP_NOACTIVATE | SWP_NOZORDER);
	}
	}

[roman-yepishev]

A crude version of how this may work is roman-yepishev@3385880, however it changes the behavior dramatically (hides the window before switching to/from full-screen), which is likely not expected by the clients. Additionally the example app had issues redrawing with this enabled so this does not look like a good solution.