Unable to switch between more than one instance of application

[ydewit]

I am using PopOS1 21.04 and with packages up to date (apt update $ apt upgrade)

Steps to reproduce:

1. For example, install STS
2. Launch the first STS instance
3. Check that you can switch to it using ALT-TAB, as expected
4. Now, launch a second STS instance
5. Note that only one icon shows up in the app switcher and you can only switch to the same instance.
6. Close one of the STS instances.
7. Note that you can now switch to the instance that was "hidden" before.

I remember seeing a similar behaviour around a year or more ago for a period of time, but I guess it was fixed then.

As a final note, this is important since we tend to work on multiple STS workspaces at the same time switching between them often.

[leviport]

I might be off-track here, but it sounds like this might be the intended behavior. Gnome groups instances of the same application in the Alt Tab menu. To cycle through those different instances, Alt + ` is used (that's the backtick/tilde key that's typically found above the Tab key).

Here's a quick demo, maybe it shows what I mean better:

I have 3 instances of the calculator open. At first, I Alt + Tab to select the group of Calculator apps, then if I keep the Alt key held, a dropdown of each instance appears, which I can arrow through or Alt + ` through. At the end of that recording, I also hit Alt + ` without first hitting Alt + Tab, which jumps immediately to the dropdown and allows me to choose between the different Calculator instances.

Let me know if my interpretation of this report is incorrect though.

[ydewit]

Hi @leviport, I understand what you are saying and I did not intent to prescribe what should be the solution.

The problem is that I cant access the second instance in any way: ALT+TAB shows me only one app, which may be the correct behavior, but ALT+` there shows me only one unlike, for instance, Chrome.

Could this be an app specific problem?

[leviport]

So multiple Chrome windows work correctly, but STS does not? The STS page you linked to looks like it's not a standalone application, but some addons for either Eclipse, VSCode, or Theia. Which should I start with if I want to investigate for myself?

Do you know of any other apps that behave the same way?

[ydewit]

I have downloaded and installed the STS for Eclipse binary: https://download.springsource.com/release/STS4/4.12.1.RELEASE/dist/e4.21/spring-tool-suite-4-4.12.1.RELEASE-e4.21.0-linux.gtk.x86_64.tar.gz

And then I created a ~/share/applications/sts.desktop with the following content:

#!/usr/bin/env xdg-open
[Desktop Entry]
Name=STS 4
Comment=Spring Tool Suite 4
Exec=/home/yuri/Apps/sts/SpringToolSuite4 %u
Icon=/home/yuri/Apps/sts/icon.xpm
Terminal=false
Type=Application

In chrome's case, what I see is multiple windows in ALT+` that, I think, were created within the same launch with CTRL+N. If I launch a second one using the launcher, I then see a second icon in ALT+TAB.

Note, STS/Eclipse does not allow me to launch a second window with a different workspace so this second instance launch was a welcome feature.

[senntore]

I noticed it just now after reading this issue but this is also true for Spotify, since it also doesn't allow creating multiple instances.

When you open 2 windows of it using launcher(or Ctrl+Super+Num, if it's enabled) both windows show up correctly in the launcher but not(even one like those calculator app in example above) when Alt/Super+` is used.

Edit: It is also true when only 1 window of such app is open, the window preview that we usually see when using Super+` is not there.

[ydewit]

I failed to mention in my initial description that being able to launch two or more instances of STS was working for like 2 years with PopOS. It seems to me that this behaviour was lost around the PopOS 21.04 upgrade a few months back.

[leviport]

Aha, I'm seeing it happen with Spotify now. Spotify kinda breaks if multiple instances are opened, but I do see the Alt Tab behavior get weird with those multiple instances. I'm still not seeing it happen in Eclipse, but I haven't set up STS on my Eclipse install yet.