RE: put goto-line on modeline

[Drew Adams]

    I have a comment. It is nice if the line number area in the modeline
    is highlighted if you move the mouse pointer on it. So an user can
    know the area is clickable. A tooltip is helpful but it only tells the
    mouse button and function attached to the area. But it doesn't tell the
    range of area. See png image attached to this mail. Twice I tried to
    implement modeline highlighting code, but I miscarried. What I could
    do was highlighting the major mode area.

Yes, there should be some visual feedback that a button is, well, a button
(and show its size). (Similarly for pulldown-menu buttons and hyperlinks.)
And mouseover highlighting (e.g. "raising" the button) is one good way to do
that.

Tooltips are only a last resort, when there is no other standard visual cue.
They are a general-purpose way to explain something (anything). It's better
to have specific cues for different standard classes of GUI thingies (e.g.
links different from menus different from action buttons). A tooltip can
tell you what something means, but it shouldn't be needed to tell you that
something is a button.