In October 2018, Illustrator CC 2019 introduced a slider that scales the interface for high-resolution displays.
I saw a bug in ScriptUI. If you insert
dropdownlistin the script interface and run the script in Illustrator, where the UI Scaling is not small, the text in the lines is distorted.
In Adobe Community there was a report that the borders of the dropdown are cut off, similarly seen in my example. One of the participants said that he encountered this when he had scaled the interface of Illustrator.
When Illustrator CC 2020 came out, they fixed the bugs because the dropdown in ScriptUI looks correct at all UI scales. In the meantime, some users who are still working in CC 2019 with UI scaling may encounter this problem. As a solution, you can introduce a check for the version of Illustrator and the current UI scale value when you run the script.
var aiVersion = parseInt(app.version);
var scalePref = app.preferences.getRealPreference('UIPreferences/appScaleFactor');
var scaleErr = 'If you have a problem displaying the dropdown list, disable the UI scaling in Ai prefs';
if (aiVersion == 23 && scalePref > 1) alert(scaleErr);