When max-width is specified on the left column content of VisualSplitter, resizing the left column beyond the max-width will eventually cause the right column to shrink to its minimum width. It is expected that the right column width does not change beyond the max-width of the left column.

Reproducible in 2019.3.0f6 and 2020.1.0a22. There are not currently any windows which use max-width with VisualSplitter so some tweaking of existing stylesheets will be necessary to reproduce this behavior.

1. Open unity\External\Resources\editor_resources\Assets\Editor Default Resources\StyleSheets\SettingsWindowCommon.uss in a text editor
2. Add 'max-width: 300px' to the style for 'settings-tree-imgui-container', then save and close the file
3. Build and run Unity
4. Open any project, and from the top toolbar open 'Edit > Preferences'
5. Drag the divider in the Preferences window all the way to the right

The left column of the Preferences window will stop growing once it reaches its maximum width. Dragging the cursor beyond that maximum width to the edge of the window will cause the right column to shrink in size.

Expected behavior is that neither the left or right columns change in size once the left column grows to maximum width.

See attached gif