Anybody else having trouble with the setWidth function? The example here is "300", but if you change the number, the sidebar is the same width. I've tried a few times on a clean spreadsheet.
https://developers.google.com/apps-script/guides/dialogs#custom_sidebars
Google Scripts now ignore the setWidth() method, and the sidebar width is now fixed at 300px. From the release notes:
In Google Docs and Forms, sidebars now ignore the setWidth() method; they cannot be changed from the default width of 300px. This change was applied to the new version of Sheets in the previous week's release.