Wrote code for a new utility window in the Windows backend to replace the initialParent.

redo/windows/uipriv_windows.h

@@ -104,3 +104,7 @@ extern void queueResize(uiControl *);
 extern void doResizes(void);
 extern void moveWindow(HWND, intmax_t, intmax_t, intmax_t, intmax_t);
 extern void moveAndReorderWindow(HWND, HWND, intmax_t, intmax_t, intmax_t, intmax_t);
+
+// utilwindow.c
+extern const char *initUtilWindow(HICON, HCURSOR);
+extern void uninitUtilWindow(void);

redo/windows/utilwin.c

@@ -0,0 +1,80 @@
+// 14 may 2015
+#include "uipriv_windows.h"
+
+// The utility window is a special window that performs certain tasks internal to libui.
+// It is not a message-only window, and it is always hidden and disabled.
+// Its roles:
+// - It is the initial parent of all controls. When a control loses its parent, it also becomes that control's parent.
+// - It handles WM_QUERYENDSESSION and console end session requests.
+// - It has a timer to run resizes.
+
+#define utilWindowClass L"libui_utilWindowClass"
+
+HWND utilWindow;
+
+#define resizeTimerID 15				/* a safe number */
+#define resizeTimerInterval 15
+
+static LRESULT CALLBACK utilWindowWndProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
+{
+	LRESULT lResult;
+
+	if (handleParentMessages(hwnd, uMsg, wParam, lParam, &lResult) != FALSE)
+		return lResult;
+	switch (uMsg) {
+	case WM_QUERYENDSESSION:
+	case msgConsoleEndSession:
+		// TODO block handler
+		if (shouldQuit()) {
+			uiQuit();
+			return TRUE;
+		}
+		return FALSE;
+	case WM_TIMER:
+		if (wParam != resizeTimerID)
+			break;
+		if (SetTimer(utilWindow, resizeTimerID, resizeTimerInterval, NULL) == 0)
+			logLastError("error resetting resize timer in utilWindowWndProc()");
+		doResizes();
+		return TODO;
+	}
+	return DefWindowProcW(hwnd, uMsg, wParam, lParam);
+}
+
+const char *initUtilWindow(HICON hDefaultIcon, HCURSOR hDefaultCursor)
+{
+	WNDCLASSW wc;
+
+	ZeroMemoryW(&wc, sizeof (WNDCLASSW));
+	wc.lpszClassName = utilWindowClass;
+	wc.lpfnWndProc = utilWindowWndProc;
+	wc.hInstance = hInstance;
+	wc.hIcon = hDefaultIcon;
+	wc.hCursor = hDefaultCursor;
+	wc.hbrBackground = (HBRUSH) (COLOR_BTNFACE + 1);
+	if (RegisterClass(&wc) == 0)
+		return "registering utility window class";
+
+	utilWindow = CreateWindowExW(0,
+		utilWindowClass, L"libui utility window",
+		WS_OVERLAPPEDWINDOW,
+		0, 0, 100, 100,
+		NULL, NULL, hInstance, NULL);
+	if (utilWindow == NULL)
+		return "creating utility window";
+	// and just to be safe
+	EnableWindow(utilWindow, FALSE);
+
+	if (SetTimer(utilWindow, resizeTimerID, resizeTimerInterval, NULL) == 0)
+		return "starting resize timer";
+}
+
+void uninitUtilWindow(void)
+{
+	if (KillTimer(utilWindow, resizeTimerID) == 0)
+		logLastError("error stopping resize timer in uninitUtilWindow()");
+	if (DestroyWindow(utilWindow) == 0)
+		logLastError("error destroying utility window in uninitUtilWindow()");
+	if (UnregisterClass(utilWindowClass, hInstance) == 0)
+		logLastError("error unregistering utility window class in uninitUtilWindow()");
+}