ENH: unify fonts in non-code boxes in Builder components dialog (Win32)

In Windows, wx.SYS_DEFAULT_GUI_FONT should be used to get default dialog font.
Because font size of wx.SYS_SYSTEM_FIXED_FONT is different from that of wx.SYS_DEFAULT_GUI_FONT in Windows, size of _codeFont must be set to size of _mainFont.