Yes, I can recreate that.
One 'fix' is to go Tools > My Preferences > Appearance and set to the colour scheme to 'system'?
(Do people still use F2 any more, and not double-click? Double-clicking is what I've always used, set as default for my clients, and works with any colour scheme)
Glad to hear it is reproducible.
Good find with the system theme, that does seem to be a workaround.
Personally I will always prefer a keyboard shortcut, and try to use them whenever possible.
Having to reach for the mouse only slows me down.
(My background is in programming, where using a mouse is sacrilege)
Thomas Rizzuto
With an open Quote, on the Document Items tab, pressing F2 for a column will open up the lookup window as expected.
(In this case I'm using the "Item Type" column, but seems to be the same for any column with valid lookup)
Once that lookup window has closed, pressing F2 again won't open the lookup window, and instead just selects the entire contents of the selected text box.
Changing to a different tab, such as "Sale Info" and then back to the "Document Items" tab allows F2 lookup to work, but again only on the first use.
I've also verified that the lookup window isn't just hidden or offscreen.
Attached is a video of this behavior.
Found a somewhat similar topic but from 3 years ago, so I'm not sure of its relevance:
https://tickets.quotewerks.com/support/discussions/topics/9000058793