The system tray popups in Plasma5 are a brilliant invention to make the system tray more consistent. But there will always be SNIs (Status Notifier Items) or system tray applets (e.g. unread messages applet) that don't provide the same behavior. I didn't find any Human Interface Guidelines (HIG) for system tray applets, so I guess the design should be what works best. Which kind of behavior should the keyboard layout switcher have? I give you two options:

1. Old behavior of switching the keyboard layout with left-click
2. Reveal a popup on left-click, which is consistent with the other default system tray applets e.g. Battery monitor, Clipboard and device notifier.

Related forum topic: https://forum.kde.org/viewtopic.php?f=285&t=122714

Here's some of my thoughts from the thread:

I don't switch keyboard layouts myself, so it would be great if someone who does could comment on the usability issues. Is it common to switch the keyboard layout with the mouse? Then the old approach is more convenient. But if everyone uses keyboard shortcuts to switch the layout, then a more inefficient mouse navigation doesn't matter.

Here's my perceived pros and cons for both approaches.

Popup on left-click
Pros:
- Consistency with the default system tray applets
- Place for more eye-candy or utility like a preview-functionality and a KCM-shortcut
- Mouse wheel can still be used for fast layout switching
Cons:
- Two clicks to change the layout instead of one
- Right-click menu becomes unnecessary because all functionality can be put in the popup

Switch layout on left-click
Pros:
- Doesn't change old behavior. Everything works as before
- More efficient, you can change layout with one click or by scrolling the mouse
- A layout list is provided in the right-click menu
Cons:
- Inconsistent with the default system tray applets
- Keyboard layout preview will be four clicks away (right click->configure (opens KCM)->choose layout-> click preview)

I think the choice boils down to consistency-efficiency tradeoffs, so it could go either way. I'm a little bit torn on which approach is better, now I'm slightly more in favor of the popup on left-click. I'm especially interested in input from you who switch keyboard layouts.

Edit: correcting terminology for SNI - system tray applet

Right-click menu becomes unnecessary because all functionality can be put in the popup

So the right click could be used for switching. The old behaviour is therfore almost re-established For consistency and additional options as well as eye candy stuff left click opens up the SNI.

I regularly switch between Norwegian and US English keyboards. I also use German and Japanese layouts when communicating with friends there.

But I've personally never used the mouse to change keyboard layouts. I always use a keyboard shortcut to cycle through the layouts, while keeping them specific to each separate window.

For me at least, the consistency would be the most important part.

Saabhero wrote:

Right-click menu becomes unnecessary because all functionality can be put in the popup

So the right click could be used for switching. The old behaviour is therfore almost re-established For consistency and additional options as well as eye candy stuff left click opens up the SNI.

I think this will be inconsistent with all the other SNIs an system tray applets. I haven't run into an applet that changes the right-click menu to something else.

myrjola wrote:

Saabhero wrote:

Right-click menu becomes unnecessary because all functionality can be put in the popup

So the right click could be used for switching. The old behaviour is therfore almost re-established For consistency and additional options as well as eye candy stuff left click opens up the SNI.

I think this will be inconsistent with all the other SNIs an system tray applets. I haven't run into an applet that changes the right-click menu to something else.

I agree that a simple right click should never execute an action, but I assume that he meant layout switching could be done via context menu, which would be okay.