Quoting: subdiffOk, so that on XFCE it opens the window directly only applies to Discord (and other electron apps) and not Steam, right?

Yeah, correct :) Steam just has the menu for both left and right click, however majority of other apps have left click to open app.

Has this been resolved for any of you guys? My Arch KDE setup (5.10.0) still doesn't allow open on left-click for apps like Discord, Slack.

Quoting: yochaigalHas this been resolved for any of you guys? My Arch KDE setup (5.10.0) still doesn't allow open on left-click for apps like Discord, Slack.

On KDE 5.10 the issue has been partially resolved.

The issues arose from the fact that all of those apps were still using the old legacy tray system which newer Plasma desktop doesn't support. Their response to the issue seems to have been to actually merge the function of left and right click, so now it opens the tray menu for the application, which honestly does the job for me, since everything else about Plasma desktop seems to be functioning that well.

And about the no.2 problem in my original post when Windows would open in background when clicking open in the tray, that is only related to focus stealing settings under the System settings --> Window management --> Window behavior --> Focus tab, it needs to be set to "none".

Interesting - I don't have this behavior. Left-clicking (single or double) on the discord icon for instance doesn't open a menu, or the app.