In the Appearance tab of the System Monitor applet, there is a button called "Load preset ...". Clicking it opens what looks like a popup menu, only it uses some other GUI library, because it looks different. Not only that, it also behaves differently, in that it is not treated like an actual menu.
If I decide not to load a preset, it is common habit to press Escape in order to close a menu. But in this case, this closes the whole dialog.
My Plasma version is 5.20.4
A possibly relevant merge request was started @ https://invent.kde.org/frameworks/kirigami/-/merge_requests/244
A possibly relevant merge request was started @ https://invent.kde.org/plasma/libksysguard/-/merge_requests/141
Git commit 66882a03d04ac9ef4fb8e30459e5696bf5720d99 by David Edmundson.
Committed on 25/03/2021 at 14:21.
Pushed by davidedmundson into branch 'master'.
Fix keyboard handling of preset selection
The view did not have focus correctly, due in part to this and a
We also want to prevent the plasma dialog from closing when escape is
pressed. Ideally we would have a magic solution in OverlaySheet, but
after we fixed focus it is impossible to do nicely.
shortcutOverride is only invoked on the item with real active focus, not
M +9 -0 faces/ConfigAppearance.qml