Added WS_EX_CONTROLPARENT to container and Tab on Windows.

redo/container_windows.c

@@ -72,7 +72,7 @@ HWND newContainer(void *data)
 	HWND hwnd;
 
 	hwnd = CreateWindowExW(
-		0,
+		WS_EX_CONTROLPARENT,
 		containerclass, L"",
 		WS_CHILD | WS_VISIBLE,
 		CW_USEDEFAULT, CW_USEDEFAULT,

redo/tab_windows.go

@@ -23,7 +23,7 @@ type tab struct {
 func newTab() Tab {
 	hwnd := C.newControl(C.xWC_TABCONTROL,
 		C.TCS_TOOLTIPS | C.WS_TABSTOP,
-		0)
+		C.WS_EX_CONTROLPARENT)
 	t := &tab{
 		_hwnd:	hwnd,
 	}