[release/9.0] WinForms ComboBox border and drop down button are not visible sometimes #12785
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Backport #12737 to 9.0
Fixes #12744
Fixes #12590
Customer Impact
ComboBox
drop down button disappears when switching RightToLeft property, or recreating theComboBox
for any other reason.ComboBox
focus border is not shown when TAB-ing into ToolStripComboBoxItemRoot Cause
ComboBox
controls was be drawn. It was an attempt to fix flickering of the control border when the mouse hovers over the control by reducing the number of times control is re-drawn, but we missed some cases where re-drawing was required. We don't have a better fix for the original flickering issue at the moment.Proposed changes
Regression?
Risk
Screenshots
Before
After
Test methodology
Test environment(s)
Microsoft Reviewers: Open in CodeFlow