Tiling strip's horizontal scrollbar is 5px and collides with the resize handles — a dead click zone right above it

[jesse-adapta]

Environment: Parallel Code 1.12.0 (deb), Linux (X11, GNOME). Code references verified against main @ d000fff65.

Problem

The horizontal scrollbar under the task strip is very hard to hit

What happens:

1. The scrollbar itself is a 5px sliver. Aiming at it takes real care.
2. Miss it by a few pixels upward and the cursor turns into the col-resize double-arrow (↔ with the vertical bar), which doesn't actually work

Likely cause

The col-resize zone is the panel resize handles (src/styles.css):

.resize-handle-h {
  width: 6px;
  cursor: col-resize;
}

Requests

1. Make the strip's horizontal scrollbar a drag target
2. Keep the resize handles clear of the scrollbar band, so the bottom strip of the strip is actually scroll