New diff: D25001

This diff is definitely a workaround and not the best solution, indeed it seems there was just a missing setFocusProxy() call in Konsole. I'll submit a diff there in a bit.

• Simplify a conditional statement

I did not add a message when the operation succeeds because that's already implemented somewhere else and is not necessary here too as far as I can tell.
And not sure if this is fine or I should have made a different diff for replacing the error dialog.

• Add action to switch to the last tab

As far as I know "Switch to tab n" shortcuts are not identical between applications and vary quite a bit. Some applications use 0-9, some use 1-9. Some have a "Switch to last tab" shortcut assigned to 0 or 9. Some use Ctrl, some use Alt instead or even both.
In the case of web browsers I would assume they don't use 0 because Ctrl + 0 resets the zoom level, and Firefox on Windows uses Ctrl instead of Alt, Chrome uses both Ctrl and Alt I think but I don't use Chrome.

In D24353#541721, @elvisangelaccio wrote:

This is what I get in the shortcuts dialog:

Possibly related to this warning:

KLocalizedStringPrivate::substituteSimple(): "0 instead of 1 arguments to message {Activate Tab %1} supplied before conversion

• Fix bad argument substitution in a i18nc() call

GIT_SILENT Make numberForShortcut const

• Add default shortcuts for the first 10 tabs

Use y() + height() instead of bottom() + 1