wxButton::GetDefaultSize() added for MSW and documented

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@2980 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/msw/button.cpp

@@ -131,6 +131,20 @@ wxSize wxButton::DoGetBestSize()
     return wxSize(wBtn, hBtn);
 }
 
+/* static */
+wxSize wxButton::GetDefaultSize()
+{
+    // the base unit is the height of the system GUI font
+    int wChar, hChar;
+    wxGetCharSize(0, &wChar, &hChar, NULL);
+
+    // the button height is proportional to the height of the font used
+    int hBtn = BUTTON_HEIGHT_FROM_CHAR_HEIGHT(hChar);
+
+    // and the width/height ration is 75/23
+    return wxSize((75 * hBtn) / 23, hBtn);
+}
+
 // ----------------------------------------------------------------------------
 // set this button as the default one in its panel
 // ----------------------------------------------------------------------------