Feature request: Alt-Tab like feature

[jvalrog]

I find it slow that to change to another container group I have to first open the conex menu and then navigate it with my cursor keys.

An alt+tab like shortcut would be really faster.

Behaviour could be:

• [modkey + key] (single press event): go to previous group
• [modkey + key] (keeping modkey pressed): navigate the menu with [key] single press. Activate when [modkey] is released.