UI: Fix scrollbar enablement in Scene Grid Mode

Browse Source

The UI layout math used to determine if scrollbars should be displayed
in the Scenes Dock was off by one pixel. This caused the scrollbar to
disappear when performing actions while scrolled to the bottom, such as
dragging items or resizing the dock.

...

This commit is contained in:

500 Internal Server Error

Gitea Version: 1.28.0+dev-477-g8b6ad49a5f