Visual Mode: fixed an issue where trying to apply a rotation to things that were not seen yet would cause a crash

Fixed a problem where not selected geometry and things could not be dragged when the "don't move selection if any part of it is outside of map boundary" option was enabled

Visual Mode: fixed a problem where the selection order was not kept when synchronized selection between visual and classic modes was enabled. Fixes #938

Visual Mode: fixed a problem where things directly touching the top of 3D floors were rendered with the incorrect brightness. Fixes #940

Visual Mode: changes to Eternity Engine's upper/lower texture skewing definitions are now shown in Visual Mode

Visual Mode: fixed a crash when toggling visual vertex slope picking and the map contains double-sided linedefs without a front sidedef. Fixes #928

- fixed a rare condition where skewed mid textures were not clipped correctly
- fixed a problem where translucent mid textures were not skewed correctly
- fixed a problem where sprites were skewed unintentionally

Draw Grid Mode: fixed a problem where "continuous drawing" would redraw all previously drawn shapes each time a drawing was finished. Fixes #912

(Text labels are removed because of performance issues)