[Bug] vtkScalarBarActor tick alignment and color bar border issue after v31.2.0

[galuszkm]

Bug description

In vtk.js releases later than v31.2.0, I have observed that the vtkScalarBarActor no longer aligns the ticks correctly with the color bar borders. Specifically:

• The ticks are offset from the color bar borders.
• The top and bottom segments of the color bar are visibly smaller than the middle segments.
• This visual inconsistency was not present in v31.2.0.

I compared the vtkScalarBarActor code between v31.2.0 and later versions but did not notice any obvious code changes that would directly cause this issue.

Steps to reproduce

1. Render a vtkScalarBarActor using vtkLookupTable with number of colors 9 in a version later than 31.2.0.
2. Compare the tick alignment and segment sizing to the same setup in v31.2.0.

Detailed Behavior

Below is a visual comparison between v31.2.0 and versions after 31.2.0

• Left: v31.2.0 (ticks and color bar segments properly aligned)
• Right: >v31.2.0 (ticks misaligned, top/bottom segments smaller)

Expected Behavior

• Ticks are aligned with color bar borders.
• All color segments with the same size.

Environment

• vtk.js version: 31.2.0 and >31.2.0
• Browsers: All
• OS: All