Mouse cursor is not changing to default cursor when the mouse cursor is on the scrollbar of the textarea, after the frame is blocked by dialog (basic Modality).

Step to reproduce
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1) Run the attached program.
2) Move the mouse over the textarea , you can see the default mouse cursor is changed to text cursor.
3) move the mouse over the scrollbar of the textarea, you can see the text cursor is changed to default cursor.
4) Click on 'Click Me' button. You can see a dailog , which makes the frame to be inactive.
5) Move the mouse on the textarea, you can see the default cursor is changed to Text cursor.
6) Move the mouse on the scrollbar of the textarea, If you see the mouse cursor is still text cursor, then the bug is reproduced.

I tested this with Mustang b10 , b20 & its working fine, but fails from b25 onwards to till b78. Hence this is a regression.