Sidebar extensions can define their minimum width via XSidebarPanel::getMinimalWidth. However, if this size is larger than the maximum size of the sidebar, this causes issues (resizing is broken, causes "jumping", etc.) Basically the behavior is undefined. This should be fixed, probably by increasing the maximum allowed width of the sidebar if this value is larger than the current max width.
Samuel Mehrbrodt committed a patch related to this issue. It has been pushed to "master": https://git.libreoffice.org/core/+/d0c73ce13c02c37fcc094ac6612d6a8eee2a4026%5E%21 tdf#124263 Respect XSidebarPanel::getMinimalWidth 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.
Samuel Mehrbrodt committed a patch related to this issue. It has been pushed to "master": https://git.libreoffice.org/core/+/a58391b1f61db702a5246c5a33717cbba68c5252%5E%21 Related tdf#124263 Make sure sidebar is wide enough for content 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.