Hi all. I’m on Qt 5.14.2, with a Qt Widgets based app that runs on both macOS
and Linux. I’m having trouble getting my menu bar to work.
So that things work smoothly on Linux platforms where there is a menu bar in
each main window, I have a menu bar in the .ui file that contains my main
window. That design works fine, on both platforms. Where things have gotten
bumpy is when I decided to try to make it so my app stays running even when the
last document window is closed, as is fairly typical for macOS apps; this
definitely makes sense for my app, where it would be common to close one window
and then create a new window to continue working. To make this happen, I call
setQuitOnLastWindowClosed(false), at startup in main(), after creating
QApplication and before parsing the command line and creating the initial main
window. This, in itself, seems to work fine; now the app doesn’t quit when the
last window is closed. I do this on macOS only, and the remainder of this
question applies solely to macOS; on Linux the app quits when the last window
is closed, and there is no problem.
Since the menu bar is owned by the main windows in my app, when the last window
is closed the menu bar reverts to a very minimal default state; all of the
other menus disappear. I want to have a full menu bar (perhaps minus a couple
of main-window-specific menus) in that mode, so I’ve been trying to get a
“global menu bar” working, as described in the QMenuBar doc (by making a
QMenuBar object that has no parent). I’ve tried this a couple of different
ways, but I can’t get it to work completely. The problem is always that some
of the menu items that need to be moved into the application menu on macOS
don’t move – they disappear. Specifically, this happens to the About,
Preferences, and Quit menu items. The menu bar appears fine whenever a main
window is open; the menu bar that gets created by that .ui file seems to work
perfectly. But the “global” menu bar that I create myself is missing those
items.
I’ve tried creating the global menu bar either when the last window closes
(i.e., on demand), or at startup before the first main window is created; the
behavior is the same either way. I’ve tried creating the Quit menu item the
easy way, with:
fileMenu->addAction("Quit SLiMgui", this, &QtSLiMAppDelegate::dispatch_quit,
Qt::CTRL + Qt::Key_Q);
or the long way, creating the QAction and then setting its shortcut, connecting
it, and finally adding it to fileMenu; the behavior is the same either way.
I’ve tried poking the menu bar after I’ve finished creating it, by calling
toNSMenu(); makes no difference. I’ve tried setting the menu role for the Quit
item to QuitRole, before adding it to fileMenu, or leaving it as the default;
makes no difference.
In all cases, I can output the structure of the menu bar immediately after I
create it and I see (showing just the File menu, where the Quit item gets added
by my code):
"File"
"About SLiMgui"
"Preferences..."
""
...
""
"Quit SLiMgui"
So the items in question are present, in the File menu where I put them. But
then when I click on the menu bar in my app, these menu items – about,
preferences, and quit – are not in the File menu, nor are they in the
application menu; they’re just gone. They have been filtered out, somewhere
down the road.
Since this global menu bar stuff is macOS-specific code anyway, I would happily
just add the menu items to the application menu myself, avoiding Qt’s
relocation logic. However, as far as I can tell the QMenuBar object that I
create doesn’t have an application menu in it; that seems to be private. So
Qt’s migration code isn’t doing the right thing, and I can find no way to just
do the right thing on my own. I’m running out of ideas. Is this just a bug,
or am I doing something wrong? If it’s a bug, is there a way to trigger the
menu item migration myself in a way that would work?
Thanks for any help; I’m at my wit’s end.
Cheers,
-B.
Benjamin C. Haller
Messer Lab
Cornell University
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