Bug#739577: freeciv-client-gtk: unit/tile info tied to middle mouse button only

[Jacob Nevins]

> Overally, it would be nice if there was an alternative way to
> trigger this functionality, perhaps ctrl + LMB or some such.  Some
> googling suggests alt + LMB might trigger it on some platforms,

Alt+LMB is indeed supported by the Freeciv Gtk client as the alternative
to middle-click; this is documented in the 'Controls' section of the
online help.

In general, other modifier+button combinations are pretty well used for
other functions, so I don't see much scope for adding a third
alternative.

> but that moves a window in X11 (and even in fullscreen mode, doesn't
> seem to have any effect here).

It's more likely to be your window manager / desktop environment that
eats Alt+mouse than X11 itself. For instance, I think Xfce has the
behaviour you describe. 

> However, e.g. the thinkpad notebooks can use the middle button
> to emulate a scrollwheel if held, which is extremely useful but
> interferes with this.  (Curiously - just tapping the middle mouse button
> normally retains its function, e.g. pastes in a terminal, but has no
> effect in the freeciv client.)

Not sure why this might be, but the effect of tapping would be to bring
up the info popup only momentarily, which isn't very useful, so I'm not
inclined to spend time investigating the discrepancy.