Edit Box – Custom Context Menu

The Undo and Redo commands require extra work to track line changes they cause.  These commands need to be intercepted before the operation is performed, because the wrong lines are detected as being changed.  There are three ways that these commands are activated, by their actions (Edit menu and tool bar), keys (Control+Z and Control+Y) and from the default context menu of the edit box.

The actions can be caught by reimplementing the undo() and redo() functions in the EditBox class.  The keys can be caught by adding checks for the key sequences in the key press event handler.  But the context menu can not be caught (at least none that I could find).

Instead of using the default context menu, a custom context menu will be used for EditBox.   The necessary actions are already present.  A context menu can easily be added either by adding each action individually or creating a list of actions and then adding the list.  The later method was used and after adding the actions, plus the desired menu separators, the setContextMenuPolicy() function is used to tell EditBox to use these actions instead of the default context menu.  A side benefit of the custom context menu is that the items have the icons assigned to the actions (the default context menu does not display any icons).

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