Sidebar panel can only be resized by dragging the top edge

[zhoupeiyu]

Description

The right-side folder panel can only be resized by dragging its top area. Dragging the middle or bottom portion of the panel border does nothing.

Expected Behavior

The entire vertical edge of the panel should be draggable for resizing, not just the top portion.

Steps to Reproduce

1. Open a project in Mori
2. Expand the right-side folder panel
3. Try to drag the panel border from the middle area to resize — nothing happens
4. Drag from the top area — resizing works

Environment

• macOS
• Mori latest release