[Guy Harris <gharris@xxxxxxxxxxxx>]

> It should not be available if you don't have a proto-tree line selected.

Hmm.  Arguably, context menus should apply to whatever's under the mouse
cursor (which appears to be applied in a fairly broad sense in at least
some Windows applications, e.g. in a pane with multiple items in the
pane, I've seen places where it offers functions that apply to the item
under the mouse, as well as functions that apply to all the stuff in the
pane), so perhaps it should either

	1) select the protocol tree line under the mouse (I think that's
	   what NetMon does)

or

	2) apply to the line under the mouse rather than to the selected
	   line.