Fix best size calculation for buttons with bitmaps in wxMSW.

Add the bitmap margins to the bitmap size, not the total button size.

This fixes the buttons becoming unnecessarily tall as soon as they were
assigned even a tiny bitmap.

Closes #16536.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/branches/WX_3_0_BRANCH@78118 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/changes.txt

@@ -591,6 +591,7 @@ wxMSW:
 - Fix compilation with C++Builder XE compiler (Nichka).
 - Fix best height of wxSlider with labels but without ticks (Artur Wieczorek).
 - Fix initial text value of wxSpinCtrlDouble (Laurent Poujoulat).
+- Fix best size calculation for bitmaps with buttons (Artur Wieczorek).
 
 
 3.0.2: (released 2014-10-06)

src/msw/anybutton.cpp

@@ -519,8 +519,9 @@ void wxAnyButton::AdjustForBitmapSize(wxSize &size) const
 {
     wxCHECK_RET( m_imageData, wxT("shouldn't be called if no image") );
 
-    // account for the bitmap size
-    const wxSize sizeBmp = m_imageData->GetBitmap(State_Normal).GetSize();
+    // account for the bitmap size, including the user-specified margins
+    const wxSize sizeBmp = m_imageData->GetBitmap(State_Normal).GetSize()
+                                + 2*m_imageData->GetBitmapMargins();
     const wxDirection dirBmp = m_imageData->GetBitmapPosition();
     if ( dirBmp == wxLEFT || dirBmp == wxRIGHT )
     {
@@ -535,9 +536,6 @@ void wxAnyButton::AdjustForBitmapSize(wxSize &size) const
             size.x = sizeBmp.x;
     }
 
-    // account for the user-specified margins
-    size += 2*m_imageData->GetBitmapMargins();
-
     // and also for the margins we always add internally (unless we have no
     // border at all in which case the button has exactly the same size as
     // bitmap and so no margins should be used)