a single table cell is drawn as selected when selecting a previous search query

[ronso0]

Noticed this a few times while testing #12063 (no changes to tracks table or search box, just searchqueryparser).

Can not reproduce but this is what I did IIRC

• type a query, hit Return to save it
• go to tracks table, select tracks, change selection, edit tags etc.
• clear search
• select a previous query
• the top-left table cell is drawn like if it was selected (coloured background)
• switching to the tracks table selects the entire row with the previously 'selected' cell being focused (white border)

This shouldn't be possible since we setSelectionBehavior(QAbstractItemView::SelectRows); in WLibraryTableView.
My Qt version didn't change either (still on 5.12.8) 🤷‍♂️

[ronso0]

Could reproduce it (only on first attempt after start):

• start Mixxx
• go to searchbox, type played:N (adjust N to get some results), don't hit Enter to not jump to the tracks table
• wait for the debounce timer to expire, search results are displayed
• change query to played:=N, wait
• top-left cell is selected

Probably a regression from 400bb8f/a381d33f4ad246077bf216fed320b0d6c4400643
Maybe missing initialization of prevRow/prevColumn

[Holzhaus]

Maybe we need to reset the selection Model.