The Options Dialog
This dialog is invoked by clicking the Options button. The dialog supports changing the highlighting color, whether to use a pen or fill or both, and the fill's opacity. The Square Size is used when doing Appearance mode comparisons: the smaller the size the more fine-grained the highlighting is—and the slower to compute. The Rule width determines the thickness of the margin rules which are used to indicate the vertical position of differences; the rules can be switched off using a Rule width of 0.
Dock Windows
The Controls, Actions, Margins, Zoning, and Log views are in dock widgets—these can be dragged into other dock areas (in which case they will reshape themselves as necessary), or dragged to float free. The Margins, Zoning, and Log views can also be closed; right click a dock area splitter and check their checkbox to open them again. These views may be shown tabbed: if there is enough space they can be dragged out of their tabs and all shown in full.