To reproduce:
Resize the code editor so it is at minimum width.
Paste this example code into the Resources tab.
Click the Script Code tab, then go back to the Resources tab.
Horizontal scroll to the right -- you can't scroll far enough to see all of the code. Also the cursor can be moved out of the window if you are one of the a cut-off lines and use the arrow keys.
The only way to see all of the text is to make the whole window wider.
If you start typing anywhere, the hidden text will become visible once your new line is longer than the hidden text line.
It also seems to help to close and re-open the button editor.
On Win 11 it's slightly harder to see in some cases (where all/most of the text is visible but you should be able to scroll on character farther to see the blank space at the end of the line) as it's harder to tell if the scrollbar is all the way to the end or not, due to the lack of visible bounds on Win 11's scrollbars.
@ lxp
I just realized the bug doesn't trigger until you have left the Resources tab at least once after pasting the code into it.
(I edited my original post to reflect this)
We've tracked down the cause and have a fix on the way. Unfortunately, we're in the middle of re-writing a lot of the editor, which isn't finished yet, so the change may not be in the very next update, but shouldn't be too long away.
As a workaround, pushing End should still take you to the very end of the line.
Thanks for reporting the issue, as we had not noticed it ourselves until you pointed it out!