An annoyance with Kubuntu and Intellij where they share the same key mappings disallowing you from opening the VCS Operations Popup. You could change Intellij’s key maps but if you’re working on different platforms at home and work, teaching yourself different key mappings for the same shortcut isn’t ideal.
On Kubuntu (14.04), to change the Alt+Backquote keymap go to System Settings > Window Management > Task Switcher and find the ‘Current application’ area. You choose, either create new mappings or do what I did and set to none. Wallah! Intellij Alt+Backquote now works.