Comment # 12 on bug 1045798 from Stefan Hundhammer

One reason why you can't see the widget shortcuts in this scenario is that this
widget theme (most likely one that comes with KDE) does not show the shortcuts
at all. I consider that a bug of that widget theme, but this is probably yet
another example of designers thinking "function be damned, design is what I
care for" (instead of the old-fashioned "form follows function").

Using another widget theme that actually shows those shortcuts might give more
enlightenment what's happening.