Open Radar

 
Area:
AppKit

Summary:

Collapsing & expanding NSSplitView sidebars rapidly breaks the layout of text in NSTextViews. (See screencapture.mp4) When it breaks, the view hierarchy contains many _NSClipOverhangViews (see screenshots "broken clip view" 1 and 2).

Steps to Reproduce:

- Open the example project from the .zip I attached.
- Trigger "Show Sidebar" from the menu rapidly using a keyboard shortcut (Cmd-Ctrl-S)

To set up a new project with the same problem from scratch:

- Use a NSSplitViewController in the Storyboard with the left item as "Sidebar", and the right view controller containing a scrollable text view; the scroll view is pinned to all 4 sides of its view controller's contentView
- Wire "View > Show Sidebar" to "First Responder"'s -toggleSidebar:
- Show a long text in the text view
- Trigger "Show Sidebar" rapidly


Expected Results:

The text view  layouts its contents to fit the width of the container at every stage of the animation and after the collapse/expansion is finished.

Actual Results:

The text view ends up displaying text too wide so you have to scroll horizontally; or it displays the text in too narrow a container.

Version/Build:

Xcode Version 10.1 (10B61)
macOS 10.14.2 (18C54)