[Accessibility] Incorrect ScreenReader blue rectangle for a new character in TextCompoments

[vladimir-krestov]

Related issues:

• [Accessibility Insights] An element of the given ControlType must support the Text pattern for edit controls: TextBox/MaskedTextBox/ComboBox/NumericUpDown/DomainUpDown #1588
• [Accessibility] An element of the given ControlType must support the Text pattern for PropertyGrid: Text tree items #3683
• DataGridView's edit controls don't support UIA Text pattern as required by UIA rules #2786
• [Accessibility] ToolStripTextBox must support Text pattern #3860

The issue reproduces only in a context of Text pattern implementation

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• .NET Core Version: 5.0.0-rc.1.20431.5

• Have you experienced this same bug with .NET Framework?: No (Text pattern is not implemented)

Problem description:

• ScreenReader doesn't show the blue rectangle around an added character when typing a text in ToolStripTextBox, DataGridViewTextBoxCell, PropertyGridView.GridViewEdit

  

Expected behavior:

• ScreenReader should show the blue rectangle for a new character like in TextBox
  

Minimal repro:

• Create .Net 5.0 app
• Add ToolStripTextBox, DataGridViewTextBoxCell, PropertyGridView.GridViewEdit to the app
• Run the app and Narrator
• Try to type a text in a text field

[merriemcgaw]

@vladimir-krestov is this a regression for TextBoxes as well? Do we have a theory as to what we're not updating for Narrator to recognize the new characters are happening. I'm reluctant to push this in so late in 5.0, but I can chat with @guybark to see what his thoughts are about the urgency of this issue.

[vladimir-krestov]

@merriemcgaw I prepared the fix (#3969), we need to raise Text_TextChangedEvent only to Narrator shows the blue rectangle correctly like in RichTextBox.
I think we can add this to .Net 5.0 as part of adding Text pattern