use focused bitmap as fallback for the hover one

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@36078 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/latex/wx/bbutton.tex

@@ -40,7 +40,11 @@ to be set.}
 \twocolitem{\windowstyle{focus}}{Bitmap shown when the button has keyboard
 focus but is not pressed.}
 \twocolitem{\windowstyle{hover}}{Bitmap shown when the mouse is over the
-button (but it is not pressed).}
+button (but it is not pressed). Notice that if hover bitmap is not specified
+but the current platform UI uses hover images for the buttons (such as Windows
+XP or GTK+), then the focus bitmap is used for hover state as well. This makes
+it possible to set focus bitmap only to get reasonably good behaviour on all
+platforms.}
 \end{twocollist}
 
 

include/wx/msw/bmpbuttn.h

@@ -51,7 +51,9 @@ public:
     virtual void DrawButtonDisable( WXHDC dc, int left, int top, int right, int bottom, bool with_marg );
 
 protected:
+    // reimplement some base class virtuals
     virtual wxSize DoGetBestSize() const;
+    virtual void OnSetBitmap();
 
     // invalidate m_brushDisabled when system colours change
     void OnSysColourChanged(wxSysColourChangedEvent& event);

src/msw/bmpbuttn.cpp

@@ -26,6 +26,7 @@
 
 #include "wx/msw/private.h"
 #include "wx/image.h"
+#include "wx/msw/uxtheme.h"
 
 // ----------------------------------------------------------------------------
 // macros
@@ -204,6 +205,26 @@ void wxBitmapButton::OnMouseEnterOrLeave(wxMouseEvent& event)
     event.Skip();
 }
 
+void wxBitmapButton::OnSetBitmap()
+{
+    // if the focus bitmap is specified but hover one isn't, use the focus
+    // bitmap for hovering as well if this is consistent with the current
+    // Windows version look and feel
+    //
+    // rationale: this is compatible with the old wxGTK behaviour and also
+    // makes it much easier to do "the right thing" for all platforms (some of
+    // them, such as Windows XP, have "hot" buttons while others don't)
+    if ( !m_bmpHover.Ok() &&
+            m_bmpFocus.Ok() &&
+                wxUxThemeEngine::GetIfActive() )
+    {
+        m_bmpHover = m_bmpFocus;
+    }
+
+    // this will redraw us
+    wxBitmapButtonBase::OnSetBitmap();
+}
+
 // VZ: should be at the very least less than wxDEFAULT_BUTTON_MARGIN
 #define FOCUS_MARGIN 3