ReadOnly TextView's broken scrolling after version update

Describe the bug Another breaking change I came across when upgrading from v1.9.0 to 1.12.1, is that I cannot scroll my read-only TextView correctly any more.

To Reproduce Steps to reproduce the behavior:

1. Add a quite short TextView, so that you don’t have to insert a lot of text to reproduce the error.
2. Set it’s ReadOnly property to true and its Text property to several lines, such that they exceed its height.
3. Scroll down to the end and then try to scroll up again, using the keyboard’s up and down arrows.
4. Notice that you cannot scroll back to the top. If you type a character or use the mouse wheel, it’s as if it gets unstuck for a while and then you might be able to scroll to the top.
5. Also, notice that it’s sluggish, the cursor might move a little right or left when changing lines and get stuck “randomly”.

Expected behavior To scroll seamlessly, like I used to.

Screenshots Here, I demonstrate the different behavior between the two versions. The read-only is the bottom one, in the “output” frame.

Desktop (please complete the following information):

• OS: Windows
• Version 10

[tig]

Thank you for reporting this. Really appreciate you providing repro instructions.

[tig]

If someone can do a PR for this into develop I’ll grab it and release v1.13.2 asap!