Fix for #15715: NULL check required in wxRichTextBuffer::SetStyleSheetAndNotify()


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75311 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Fix for #15718: wxSymbolPickerDialog crashes on ampersand character


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@75313 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775