Check if the colour string is not empty before trying to pull something out of it.  Fixes #15210.

git-svn-id: http://svn.wxwidgets.org/svn/wx/wxPython@74021 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
fix docstring typo

git-svn-id: http://svn.wxwidgets.org/svn/wx/wxPython@74022 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
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git-svn-id: http://svn.wxwidgets.org/svn/wx/wxPython@74023 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
reswigged

git-svn-id: http://svn.wxwidgets.org/svn/wx/wxPython@74024 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
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git-svn-id: http://svn.wxwidgets.org/svn/wx/wxPython@74025 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775