Fixed Tabs on Windows having undesirable tab stop behavior. This doesn't work correctly in wine, and I can confirm for the first time that it actually is a bug in wine!

redo/tab_windows.c

@@ -80,3 +80,27 @@ LONG tabGetTabHeight(HWND hwnd)
 	}
 	return tallest;
 }
+
+void tabEnterChildren(HWND hwnd)
+{
+	DWORD style, xstyle;
+
+	style = (DWORD) GetWindowLongPtrW(hwnd, GWL_STYLE);
+	xstyle = (DWORD) GetWindowLongPtrW(hwnd, GWL_EXSTYLE);
+	style &= ~((DWORD) WS_TABSTOP);
+	xstyle |= WS_EX_CONTROLPARENT;
+	SetWindowLongPtrW(hwnd, GWL_STYLE, (LONG_PTR) style);
+	SetWindowLongPtrW(hwnd, GWL_EXSTYLE, (LONG_PTR) xstyle);
+}
+
+void tabLeaveChildren(HWND hwnd)
+{
+	DWORD style, xstyle;
+
+	style = (DWORD) GetWindowLongPtrW(hwnd, GWL_STYLE);
+	xstyle = (DWORD) GetWindowLongPtrW(hwnd, GWL_EXSTYLE);
+	style |= WS_TABSTOP;
+	xstyle &= ~((DWORD) WS_EX_CONTROLPARENT);
+	SetWindowLongPtrW(hwnd, GWL_STYLE, (LONG_PTR) style);
+	SetWindowLongPtrW(hwnd, GWL_EXSTYLE, (LONG_PTR) xstyle);
+}

redo/tab_windows.go

@@ -23,9 +23,7 @@ type tab struct {
 func newTab() Tab {
 	hwnd := C.newControl(C.xWC_TABCONTROL,
 		C.TCS_TOOLTIPS | C.WS_TABSTOP,
-		// this is needed to have the tab contents be tab stop
+		0)		// don't set WS_EX_CONTROLPARENT here; see uitask_windows.c
-		// TODO this seems to override WS_TABSTOP; it seems I have to undo making the containers children - http://stackoverflow.com/questions/1153981/tab-order-in-tab-control-with-nested-dialogs-ws-ex-controlparent
-		C.WS_EX_CONTROLPARENT)
 	t := &tab{
 		_hwnd:	hwnd,
 	}

redo/uitask_windows.c

@@ -4,15 +4,18 @@
 #include "_cgo_export.h"
 
 // note that this includes the terminating '\0'
-#define NAREACLASS (sizeof areaWindowClass / sizeof areaWindowClass[0])
+// this also assumes WC_TABCONTROL is longer than areaWindowClass
+#define NCLASSNAME (sizeof WC_TABCONTROL / sizeof WC_TABCONTROL[0])
 
 void uimsgloop(void)
 {
 	MSG msg;
 	int res;
-	HWND active;
+	HWND active, focus;
-	WCHAR classchk[NAREACLASS];
+	WCHAR classchk[NCLASSNAME];
 	BOOL dodlgmessage;
+	BOOL istab;
+	BOOL idm;
 
 	for (;;) {
 		SetLastError(0);
@@ -23,21 +26,31 @@ void uimsgloop(void)
 			break;
 		active = GetActiveWindow();
 		if (active != NULL) {
-			HWND focus;
+			// bit of logic involved here:
-
+			// we don't want dialog messages passed into Areas, so we don't call IsDialogMessageW() there
+			// as for Tabs, we can't have both WS_TABSTOP and WS_EX_CONTROLPARENT set at the same time, so we hotswap the two styles to get the behavior we want
+			// theoretically we could use the class atom to avoid a wcscmp()
+			// however, raymond chen advises against this - http://blogs.msdn.com/b/oldnewthing/archive/2004/10/11/240744.aspx (and we're not in control of the Tab class, before you say anything)
+			// we could also theoretically just send msgAreaDefocuses directly, but what DefWindowProc() does to a WM_APP message is undocumented
 			dodlgmessage = TRUE;
+			istab = FALSE;
 			focus = GetFocus();
 			if (focus != NULL) {
-				// theoretically we could use the class atom to avoid a wcscmp()
+				if (GetClassNameW(focus, classchk, NCLASSNAME) == 0)
-				// however, raymond chen advises against this - http://blogs.msdn.com/b/oldnewthing/archive/2004/10/11/240744.aspx
-				// while I have no idea what could deregister *my* window class from under *me*, better safe than sorry
-				// we could also theoretically just send msgAreaDefocuses directly, but what DefWindowProc() does to a WM_APP message is undocumented
-				if (GetClassNameW(focus, classchk, NAREACLASS) == 0)
 					xpanic("error getting name of focused window class for Area check", GetLastError());
 				if (wcscmp(classchk, areaWindowClass) == 0)
 					dodlgmessage = FALSE;
+				else if (wcscmp(classchk, WC_TABCONTROL) == 0)
+					istab = TRUE;
 			}
-			if (dodlgmessage && IsDialogMessageW(active, &msg) != 0)
+			if (istab)
+				tabEnterChildren(focus);
+			// TODO this goes into an infinite loop on a blank tab
+			if (dodlgmessage)
+				idm = IsDialogMessageW(active, &msg);
+			if (istab)
+				tabLeaveChildren(focus);
+			if (idm != 0)
 				continue;
 		}
 		TranslateMessage(&msg);

redo/winapi_windows.h

@@ -90,6 +90,8 @@ extern void setTabSubclass(HWND, void *);
 extern void tabAppend(HWND, LPWSTR);
 extern void tabGetContentRect(HWND, RECT *);
 extern LONG tabGetTabHeight(HWND);
+extern void tabEnterChildren(HWND);
+extern void tabLeaveChildren(HWND);
 
 // table_windows.go
 extern LPWSTR xWC_LISTVIEW;