1 files changed, 30 insertions, 1 deletions

diff --git a/alf/alflayout.cpp b/alf/alflayout.cpp
index c05d355..73b05a8 100644
--- a/alf/alflayout.cpp
+++ b/alf/alflayout.cpp
@@ -102,6 +102,18 @@ ALF_Layout_ForwardFont(ALFLayout *layout, HWND window, HFONT font, LPARAM redraw
     }
 }
 
+static void
+ALF_Layout_ForwardBgColor(ALFLayout *layout, HWND window, WPARAM wparam, LPARAM lparam)
+{
+    (void)window;
+
+    ALF_FOR_LIST(ALFWidgetPriv, list, &layout->widgets, i) {
+        if (i->flags & ALF_LAYOUT_INHERITBGCOLOR) {
+            SendMessage(i->hwnd, ALF_WM_SETBGCOLOR, wparam, lparam);
+        }
+    }
+}
+
 void
 ALF_Layout_EnsureRowExists(ALFLayout *layout, int rowno)
 {
@@ -305,6 +317,8 @@ ALF_Layout_Apply(ALFLayout* layout, HWND window)
     // now apply positions to widgets
     HDWP hdwp = BeginDeferWindowPos(layout->nColumns * layout->nRows);
 
+    ALFColor bgcolor = (ALFColor)SendMessage(window, ALF_WM_GETBGCOLOR, 0, 0);
+
     ALF_FOR_LIST(ALFWidgetPriv, list, &layout->widgets, c) {
         int col = c->x;
         int row = c->y;
@@ -320,10 +334,15 @@ ALF_Layout_Apply(ALFLayout* layout, HWND window)
         if (c->flags & ALF_LAYOUT_CUSTOMPOS) {
             hdwp = (HDWP)SendMessage(c->hwnd, ALF_WM_APPLYSIZE, (WPARAM)hdwp, (LPARAM)&r);
         } else {
+            UINT flags = SWP_NOACTIVATE | SWP_NOZORDER | SWP_NOOWNERZORDER;
+
+            if (bgcolor == ALF_COLOR_TRANSPARENT)
+                flags |= SWP_NOCOPYBITS;
+
             hdwp = DeferWindowPos(hdwp,
                                 c->hwnd, 0,
                                 r.left, r.top, r.right - r.left, r.bottom - r.top,
-                                SWP_NOACTIVATE | SWP_NOZORDER | SWP_NOCOPYBITS);
+                                flags);
         }
     }
 
@@ -349,6 +368,9 @@ ALF_Layout_AddWidget(ALFLayout* layout, HWND window, const ALFAddWidgetParams* p
     if (w->flags & ALF_LAYOUT_INHERITFONT) {
         SendMessage(w->hwnd, WM_SETFONT, (WPARAM)SendMessage(window, WM_GETFONT, 0, 0), 0);
     }
+    if (w->flags & ALF_LAYOUT_INHERITBGCOLOR) {
+        SendMessage(w->hwnd, ALF_WM_SETBGCOLOR, (WPARAM)SendMessage(window, ALF_WM_GETBGCOLOR, 0, 0), 0);
+    }
 
     ALF_ListInsert(layout->widgets.prev, &w->list);
 
@@ -502,6 +524,8 @@ ALF_Layout_SetWidgetFlags(ALFLayout *layout, HWND window, HWND needle, DWORD fla
 
             if (flags & ALF_LAYOUT_INHERITFONT)
                 SendMessage(w->hwnd, WM_SETFONT, (WPARAM)SendMessage(window, WM_GETFONT, 0, 0), 0);
+            if (flags & ALF_LAYOUT_INHERITBGCOLOR)
+                SendMessage(w->hwnd, ALF_WM_SETBGCOLOR, (WPARAM)SendMessage(window, ALF_WM_GETBGCOLOR, 0, 0), 0);
 
             ALF_InvalidateLayout(window);
 
@@ -681,6 +705,11 @@ ALF_Layout_HandleMessage(ALFLayout *layout, HWND hwnd, UINT msg, WPARAM wparam,
         return TRUE;
     }
 
+    if (msg == ALF_WM_SETBGCOLOR) {
+        ALF_Layout_ForwardBgColor(layout, hwnd, wparam, lparam);
+        return TRUE;
+    }
+
     if (msg == ALF_WM_INVALIDATELAYOUT) {
         ALF_Layout_Invalidate(layout, hwnd);
         return TRUE;