Fixed Group on Windows not sending events to children. I /think/ we're done with container madness on the Windows backend...

basicctrls_windows.c

@@ -127,3 +127,36 @@ void textfieldHideInvalidBalloonTip(HWND hwnd)
 	if (SendMessageW(hwnd, EM_HIDEBALLOONTIP, 0, 0) == FALSE)
 		xpanic("error hiding TextField.Invalid() balloon tip", GetLastError());
 }
+
+static LRESULT CALLBACK groupSubProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam, UINT_PTR id, DWORD_PTR data)
+{
+	LRESULT lResult;
+	RECT r;
+
+	if (sharedWndProc(hwnd, uMsg, wParam, lParam, &lResult))
+		return lResult;
+	switch (uMsg) {
+	case WM_WINDOWPOSCHANGING:
+	case WM_WINDOWPOSCHANGED:
+		// don't use the WINDOWPOS rect here; the coordinates of the controls have to be in real client coordinates
+		if (GetClientRect(hwnd, &r) == 0)
+			xpanic("error getting client rect of Group for resizing its child Control", GetLastError());
+		groupResized((void *) data, r);
+		// and chain up
+		return (*fv_DefSubclassProc)(hwnd, uMsg, wParam, lParam);
+	case WM_NCDESTROY:
+		if ((*fv_RemoveWindowSubclass)(hwnd, groupSubProc, id) == FALSE)
+			xpanic("error removing Group subclass (which was for its own event handler)", GetLastError());
+		return (*fv_DefSubclassProc)(hwnd, uMsg, wParam, lParam);
+	default:
+		return (*fv_DefSubclassProc)(hwnd, uMsg, wParam, lParam);
+	}
+	xmissedmsg("Group", "groupSubProc()", uMsg);
+	return 0;		// unreached
+}
+
+void setGroupSubclass(HWND hwnd, void *data)
+{
+	if ((*fv_SetWindowSubclass)(hwnd, groupSubProc, 0, (DWORD_PTR) data) == FALSE)
+		xpanic("error subclassing Group to give it its own event handler", GetLastError());
+}

group_windows.go

@@ -2,6 +2,10 @@
 
 package ui
 
+import (
+	"unsafe"
+)
+
 // #include "winapi_windows.h"
 import "C"
 
@@ -9,7 +13,6 @@ type group struct {
 	*controlSingleHWNDWithText
 	child			Control
 	margined		bool
-	chainresize	func(x int, y int, width int, height int, d *sizing)
 }
 
 func newGroup(text string, control Control) Group {
@@ -21,11 +24,10 @@ func newGroup(text string, control Control) Group {
 		child:		control,
 	}
 	g.fpreferredSize = g.xpreferredSize
-	g.chainresize = g.fresize
-	g.fresize = g.xresize
 	g.fnTabStops = control.nTabStops		// groupbox itself is not tabbable but the contents might be
 	g.SetText(text)
 	C.controlSetControlFont(g.hwnd)
+	C.setGroupSubclass(g.hwnd, unsafe.Pointer(g))
 	control.setParent(&controlParent{g.hwnd})
 	return g
 }
@@ -75,19 +77,10 @@ func (g *group) xpreferredSize(d *sizing) (width, height int) {
 	return int(r.right - r.left), int(r.bottom - r.top)
 }
 
-func (g *group) xresize(x int, y int, width int, height int, d *sizing) {
-	// first, chain up to the container base to keep the Z-order correct
-	g.chainresize(x, y, width, height, d)
-
-	// now resize the child container
-	var r C.RECT
-
-	// pretend that the client area of the group box only includes the actual empty space
-	// container will handle the necessary adjustments properly
-	r.left = 0
-	r.top = 0
-	r.right = C.LONG(width)
-	r.bottom = C.LONG(height)
+//export groupResized
+func groupResized(data unsafe.Pointer, r C.RECT) {
+	g := (*group)(unsafe.Pointer(data))
+	d := beginResize(g.hwnd)
 	if g.margined {
 		// see above
 		marginRectDLU(&r, groupYMarginTop, groupYMarginBottom, groupXMargin, groupXMargin, d)

winapi_windows.h

@@ -74,6 +74,7 @@ extern void checkboxSetChecked(HWND, BOOL);
 extern void setTextFieldSubclass(HWND, void *);
 extern void textfieldSetAndShowInvalidBalloonTip(HWND, WCHAR *);
 extern void textfieldHideInvalidBalloonTip(HWND);
+extern void setGroupSubclass(HWND, void *);
 
 // init_windows.c
 extern HINSTANCE hInstance;