Mouse shortcuts
-  Click in the status bar's "Generation=..." text to change the generation count.
-  Click in the "Scale=..." text to reset the scale to 1:1.
-  Click in the "Step/Delay=..." text to reset the base step to its default value
     (specified in Preferences > Control)
     and the step exponent to 0.
-  Double-click in the edit bar's color/icon boxes to open the Set Layer Colors dialog.
-  Shift-click with the cross cursor to expand or shrink an existing selection.
     Hit the escape key to cancel the operation and restore the original selection.
-  In zoom in/out mode, use right-click or control-click to zoom in the opposite
     direction.
-  The mouse wheel can be used for zooming, regardless of cursor mode.
-  Right-click or control-click on a pattern/script/rule file in the left panel
     to open the file in a text editor.  Use Preferences > File
     to select your preferred text editor.