Subject: bug#3301: 23.0.93; menu bar bug with gtk-qt engine (KDE)

From: Stephen Berman <[email-masked]>
Date: Mon, 11 Jan 2016 10:49:02 +0100

On Mon, 11 Jan 2016 18:17:43 +1100 Alexis <[email-masked]> wrote:

> Sorry it's taken so long to get back to you. Do you still observe this
> behaviour with more recent versions of Emacs?

Yes, I still see this with current builds of emacs-25 and master (built
with GTK+ 3.14.15) running in KDE 4.14.9 on openSUSE 13.2.  However, in
checking the behavior again now, it seems this is normal in KDE: the
same thing happens when I switch focus to any KDE application by
clicking on a menu bar item.  Once difference between Emacs and other
KDE applications is that with the latter, moving the mouse pointer over
a menu bar item highlights it, even when the application window is not
in focus, whereas moving the mouse pointer over an Emacs menu bar item
does not highlight it (it gets highlighted only when it's clicked, which
brings it into focus here).  Perhaps this is a limitation of the gtk-qt
engine or a theme issue which I didn't notice or didn't obtain at the
time of my OP.  Anyway, as far as the behavior of my OP is concerned, I
now think it is not an Emacs bug.

However, there is a related behavior which appears to be Emacs-specific:
if I click with mouse-1 on an empty part of the Emacs menu bar (i.e., a
part containing no menu bar item), then the mouse pointer changes to
"move" mode for relocating the frame on the desktop by dragging.  As
with the menu bar item behavior, no other mouse or keyboard action is
possible until I hit ESC.  This happens both when switching focus to the
Emacs frame as well as when it is already in focus.  This "move"
functionality of the mouse pointer is bound to the key combination
Alt+mouse1 in my KDE (the default binding), as well as to clicking and
holding down mouse-1 on the application window title bar, but Emacs is
the only application in which clicking on an empty part of the menu bar
also activates it, and I often do that unintentionally when switching
focus, so it's annoying -- all the more so, since the mouse pointer
remains in "move" mode even after releasing the mouse button (whereas
when pressing Alt+mouse1 or clicking on the title bar, "move" mode is
active only while holding down the mouse button).  In fact, I encounter
this much more often than the menu bar item behavior, and while I don't
remember if it also happened at the time of my OP, I think I would have
noticed it then, given how frequent and annoying it is.  Moreover,
although in my OP I said I couldn't reliably reproduce the behavior, it
is 100% reprodicible with my current Emacs and KDE, in both the menu
item and "move" realizations, though again, only the latter is
Emacs-specific and hence relevant to this bug.

Steve Berman