Zone de liste déroulante.SelectedValue ne correspond pas du texte affiché lorsque DropDownStyle = DropDownList dans Windows 7

Ce correctif permettra de résoudre cette question.

Je suis tombé sur moi-même et de trouver quelques solutions de contournement. En fin de compte, j'ai roulé ma propre solution comme une sous-classe ComboBox:

//as noted here: https://connect.microsoft.com/VisualStudio/feedback/details/523272/combobox-does-not-display-selectedvalue-to-user-in-windows-7
//Windows 7 has issues with ComboBoxStyle.DropDownList mixed with AutoCompleteMode.Append or AutoCompleteMode.SuggestAppend
//this class seeks to address those problems
public class BetterComboBox : ComboBox
{
private int _windows7CorrectedSelectedIndex = -1;
private int? _selectedIndexWhenDroppedDown = null;
protected override void OnDropDown(EventArgs e)
{
_selectedIndexWhenDroppedDown = SelectedIndex;
base.OnDropDown(e);
}
private bool _onDropDownClosedProcessing = false;
protected override void OnDropDownClosed(EventArgs e)
{
if (_selectedIndexWhenDroppedDown != null && _selectedIndexWhenDroppedDown != SelectedIndex)
{
try
{
_onDropDownClosedProcessing = true;
OnSelectionChangeCommitted(e);
}
finally
{
_onDropDownClosedProcessing = false;
}
}
base.OnDropDownClosed(e);
if (SelectedIndex != _windows7CorrectedSelectedIndex)
{
SelectedIndex = _windows7CorrectedSelectedIndex;
OnSelectionChangeCommitted(e);
}
}
protected override void OnSelectionChangeCommitted(EventArgs e)
{
if (!_onDropDownClosedProcessing) _windows7CorrectedSelectedIndex = SelectedIndex;
_selectedIndexWhenDroppedDown = null;
base.OnSelectionChangeCommitted(e);
}
protected override void OnSelectedIndexChanged(EventArgs e)
{
bool alreadyMatched = true;
if (_windows7CorrectedSelectedIndex != SelectedIndex)
{
_windows7CorrectedSelectedIndex = SelectedIndex;
alreadyMatched = false;
}
base.OnSelectedIndexChanged(e);
//when not dropped down, the SelectionChangeCommitted event does not fire upon non-arrow keystrokes due (I suppose) to AutoComplete behavior
//this is not acceptable for my needs, and so I have come up with the best way to determine when to raise the event, without causing duplication of the event (alreadyMatched)
//and without causing the event to fire when programmatic changes cause SelectedIndexChanged to be raised (_processingKeyEventArgs implies user-caused)
if (!DroppedDown && !alreadyMatched && _processingKeyEventArgs) OnSelectionChangeCommitted(e);
}
private bool _processingKeyEventArgs = false;
protected override bool ProcessKeyEventArgs(ref Message m)
{
try
{
_processingKeyEventArgs = true;
return base.ProcessKeyEventArgs(ref m);
}
finally
{
_processingKeyEventArgs = false;
}
}
}

Je peux toujours reproduire cela sur Windows 10, alors j'ai pensé que je voudrais ajouter ma solution à la liste.

Private Sub LeaveComboBox(s As Object, e As EventArgs) Handles ComboBox1.Leave
Dim sender as ComboBox = DirectCast(s, ComboBox)
If sender.DroppedDown Then
' Save the correct item
Dim correctSelection as Object = sender.SelectedItem
' The core of the issue seems to be that while searching, Leave is
' triggered before DropDownClosed when you hit the TAB.
' Instead, trigger that now:
sender.DroppedDown = False
' Restore the correct item.
sender.SelectedItem = correctSelection
End If
End Sub

Remplacer la OnTextChanged méthode et il suffit de ne pas transmettre le message à la base.

protected override void OnTextChanged(EventArgs e)
{
//Eat the message so it doesn't select an incorrect value.
}