This is similar to DecTo() but can be used even if the wxSize argument has some components set to -1. Notice that we don't need IncToIfSpecified() because IncTo() already works correctly anyhow in this case. git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@72342 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775