Currently the sidebar width is limited to 400px (hard coded). Some extensions might wish to have a larger size to fit their content into. So the maximum sidebar width should be configurable.
Samuel Mehrbrodt committed a patch related to this issue. It has been pushed to "master": https://git.libreoffice.org/core/+/2a41c31a0627bf752a625f23a64eaf4d3fe82fb9%5E%21 tdf#124255 Make maximum sidebar width configurable It will be available in 6.3.0. The patch should be included in the daily builds available at https://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More information about daily builds can be found at: https://wiki.documentfoundation.org/Testing_Daily_Builds Affected users are encouraged to test the fix and report feedback.