Process status bar updates in idle events, saves a lot of unnecessary GUI work.
Further optimisations to cut down status bar update costs.
Don't update the EntityInspector on each selection change, do it when the app is idle.
No need to erase background in CamWnd and XYWnd, we redraw the entire area anyway.
Process double clicks as single clicks (#3887).
Avoid redundant XYWnd repaints.
Fix double clicks not being registered (#3887).
Register double click event handles for TexTooland TextureBrowser too.
Fix coordinate update in the status bar.
Merge changes from master.