Context menu to Signals_Slots Editor

Qt Creator's Designer should have context-menu in Signals Slots Editor. It should have those Plus and Minus options as such context menu is available in Action Editor too.

Those Plus and Minus buttons are also in quite stupid place as Action Editor has it's buttons on top of the action list. Again they should be alike.

I actually failed to see the buttons (as did my work mate) and decided to write connect's manually until some day he found the buttons (yes, stupid us, but it also tell something about bad user experience).