Summary:
I tend to press left control to wake my screen. This doesn't reveal the controls
which I found mildly annoying.

Test Plan:
Locked screen pressed random letter, it removed blur and appeared in textbox
Locked screen pressed shift, it removed blur and didn't alter textbox. It timed out as before
Pressed escape. Toggles as before

Reviewers: #plasma, broulik, ngraham

Reviewed By: #plasma, broulik, ngraham

Subscribers: ngraham, plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D12494