VS Code submenu contribution to editor/title and view/title not working correctly

[jcortell68]

Bug Description:

I was testing support for contributing a submenu via a VS Code extension. It works as expected in all the locations I tried but two:

• "editor/title"
• "view/title"

The buggy behavior is identical in both. The following will refer to only "editor/title" for simplicity, though.

The submenu appears in "invisible" fashion. The submenu's icon (a pen) should appear in the editor title toolbar, as shown here in an equivalent VS Code sample:

In Theia, the submenu does in fact end up in the editor title toolbar, but without its icon (and without its label). And so it's effectively invisible. I.e., you can't see that it's there. If you hover the mouse over that area, you will see a tooltip pop up with the submenu's name. This hints that your mouse is over something you can't see. And sure enough, if you left click there, you will end up seeing the submenu.

But even with this "workaround" you still end up with undesirable behavior. Instead of being presented with the three submenu items (Larry, Curly and Moe), you see the submenu title and icon, and you have to click yet again to get to the submenu items.

This all works intuitively in VS Code. In Theia, the implementation is off.

Note that this might seem similar to issue 12686, since it's related to the same menu insertion point ("editor/title") and it's also involves an "invisible" menu contribution. But this is a different case and I don't think fixing one will fix the other. In that other ticket, the problem is that if a menu item lacks an icon, it's shown invisibly instead of with its title. That does not apply here. Here, the submenu is given an icon (in package.json) but it does not appear in the UI. And then as mentioned above, even if it did, there's a second issue at hand...the additional click that would be necessary to get to the submenu items.

Finally, note that the example below contributes the submenu to other locations as well and the behavior seems to be good there. I.e., if you right click in the editor body, you see this

Steps to Reproduce:

git clone -b menu_bug_5 https://github.com/jcortell68/theiasandbox
cd theiasandbox
yarn
yarn start:electron

In the launched Theia, initiate the Hello World command via the Command Palette, to ensure the VS Code extension is activated and the Tree View is populated. Not technically needed to see the problem reported here.

Additional Information

• Operating System: Windows
• Theia Version: 1.39