Add missing image for floatcanvas sample

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxPython/Phoenix/trunk@73900 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Document that SplitterWindow.SetSashSize is gone.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxPython/Phoenix/trunk@73901 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Just return 0 from GetPixel if on wxGTK3

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxPython/Phoenix/trunk@73902 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
Pubsub unittest updates from Werner

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxPython/Phoenix/trunk@73903 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
More Py3 and Phoenix fixes from Mariano Reingart.

Closes #15117

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxPython/Phoenix/trunk@73904 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775