Multiple overlays from the Notes hint button

[logological]

Summary of your problem or feature request

When editing a frame in the presentation editor, there is a "Notes" field with a "?" button beside it. Clicking on this button displays an overlay at the top of the window with further help. The overlay usually disappears when clicking elsewhere in the window. However, if you click on the "?" button a second (or third, or fourth…) time when the overlay is still visible, then Sozi keeps adding more help overlays.

Version of Sozi and other relevant software

sozi-22.3.25_1648241936-1 on openSUSE Tumbleweed

Steps to reproduce the problem

1. Open the Sozi editor and add a new frame.
2. In the right pane, scroll down so that the "Notes" field is visible (but if possible, still near the bottom of the window).
3. Click on the "?" button next to the "Notes" header.
4. Repeat from Step 3.

Expected behavior

On Step 3, a help overlay should appear. On Step 4, nothing should happen.

Observed behavior

On Step 3, a help overlay appears. On Step 4, yet another help overlay appears.

Hints and solutions (optional)

While a help overlay is visible, the "?" button should be disabled.