TabPage Collection Editor: Up/Down buttons do not update enabled state correctly for first/last TabPage

[Olina-Zhang]

.NET version

.NET SDK 11.0.100-alpha.1.25619.109

Did it work in .NET Framework?

No

Did it work in any of the earlier releases of .NET Core or .NET 5+?

No, not a regression issue

Issue description

In the TabPage Collection Editor dialog, the Up and Down buttons do not reflect the correct enabled/disabled state when the selected TabPage is already at the first or last position.

It also repro in ListViewItem/ColumnHeader/ListViewGroup Collection Editor dialogs

• When the first TabPage is selected:

Up button should be disabled, but remains enabled.

• When the last TabPage is selected:

Down button should be disabled, but remains enabled.

This may mislead users into thinking the item can still be moved.

At design time, the behavior is correct(VS properties window to open): Selecting the first TabPage disables the Up button; Selecting the last TabPage disables the Down button
This behavior looks correct and matches user expectations

Steps to reproduce

1. Create a Winforms .NET project with TabControl & PropertyGrid controls
2. Select the tabControl1 as object for the propertyGrid1
3. Build and run app
4. Open TabPage Collection Editor dialog by using TabPage property in PropertyGrid
5. Observe the state of the Up/ Down button for first/last TabPage