I am trying to use SHIFT+W to razor the select clip in the timeline, but it doesn't work. Then, sometimes my keyboard focus ends up in the clip search text box, and I don't know how to return the focus to the timeline (even with clicking). When the focus ends up there, then I can't use SPACE anymore to play the timeline clip.

IIRC - UNFORTUNATELLY this is a qt/kde issue ...

The only chance to get shortcuts working again (without clicking) is using the TAB key to leave the search box.