Bug: Partial functionality of scroll in right hand pane

[Squelch]

Following on from #444.

The ability to scroll the shopping list is not immediately obvious without knowing that the red splitter bar needs to be adjusted first. This does indeed enable the scroll bars for the right hand, top (Blueprints) and bottom (Shopping List) panes. However, the scroll behaviour is inconsistent between the Materials, Blueprints, and Shopping List areas.

Reproduction:

1. Reset Window position from settings menu
2. Confirm that left hand pane (Materials) mouse scroll functions when the pointer is focused on both the main and scrollbar areas
3. Adjust on right hand side red splitter bar downwards to enable scrollbars for Blueprints and Shopping List
4. Focus pointer over Blueprints main area and use scroll wheel
5. Focus pointer over Blueprints scrollbar and use scroll wheel
6. Focus pointer over Shopping List main area and use scroll wheel
7. Focus pointer over Shopping List scroll bar and use scroll wheel

Expected

Consistent scroll behaviour for all areas that can be scrolled using the scroll wheel input

Observed

• The Materials area on the left will scroll by the same amount regardless of the pointer focus.
• The Blueprints main area scroll speed is reduced in contrast to the Materials scroll speed.
• The Blueprints scroll bar area appears to be the same as the materials scroll speed
• The Shopping List main area does not scroll when focused, but can be scrolled when the scrollbar is focused. Again, similar to that of the Materials list.

Even if a user has discovered or learned the splitter bar trick to enable the scrollbars for the right hand side, the non functioning scroll in the bottom main area may still be confusing.

See issue #491 for suggested UX improvements related to this.