Ideally, the width and height of the tabbox should fit exactly around all of the entries with no whitespace and not eliding text in a row unless that row exceeds the maximum width of the tabbox. This is how it works with many other layouts such as "Large icons". The attached screenshot shows both vertical and horizontal whitespace. I also notice that what whitespace is shown is not consistent and can change when restarting kwin, even when the same entries are shown in the same order.
Created attachment 129042 [details] Vertical and horizontal whitespace shown
A possibly relevant merge request was started @ https://invent.kde.org/plasma/kdeplasma-addons/-/merge_requests/185
Git commit 25f61ed48d9ce77d569ea9343ad3cbfb4996e78c by Ismael Asensio. Committed on 28/06/2022 at 22:39. Pushed by iasensio into branch 'master'. switchers/compact: Fix dialog sizes not getting updated Use TextMetrics to calculate text sizes and update the longest caption between different calls to the switcher (on visible changes). Also remove the minimum height constraint (20% of the screen). FIXED-IN: 5.25.3 M +37 -54 windowswitchers/compact/contents/ui/main.qml https://invent.kde.org/plasma/kdeplasma-addons/commit/25f61ed48d9ce77d569ea9343ad3cbfb4996e78c
Git commit 8fd7c783f6f21fac7eb8c6761902942db1ecea2b by Ismael Asensio. Committed on 28/06/2022 at 22:44. Pushed by iasensio into branch 'Plasma/5.25'. switchers/compact: Fix dialog sizes not getting updated Use TextMetrics to calculate text sizes and update the longest caption between different calls to the switcher (on visible changes). Also remove the minimum height constraint (20% of the screen). FIXED-IN: 5.25.3 (cherry picked from commit 25f61ed48d9ce77d569ea9343ad3cbfb4996e78c) M +37 -54 windowswitchers/compact/contents/ui/main.qml https://invent.kde.org/plasma/kdeplasma-addons/commit/8fd7c783f6f21fac7eb8c6761902942db1ecea2b