WPF ComboBox: click outside of popup suppress mouse click

Question

I use a standard WPF ComboBox control. When popup is opened and user clicks somewhere outside, popup is closed. But if there is button on the window and user clicks on it (with popup still opened), button's click handler is not executed. Popup is closed, but user has to click one more time on the button to raise click event on it.

I know that is standard behavior for this control. Have you any ideas how to bypass this behavior? Thanks!

Answer 1

I fixed some bugs with @Eng. M.Hamdy very good approach and did it in C#, also applying it to all comboboxes application wide.

Application hook:

EventManager.RegisterClassHandler(typeof(ComboBox), UIElement.PreviewMouseLeftButtonDownEvent, new MouseButtonEventHandler(FixComboBoxOutClick));

Handler code:

    private void FixComboBoxOutClick(object sender, MouseButtonEventArgs e) {
        if (sender is ComboBox combo) {
            Point comboRelativePoint = Mouse.GetPosition(combo);
            if (comboRelativePoint.X < 0 || comboRelativePoint.Y < 0 || comboRelativePoint.X > combo.ActualWidth || comboRelativePoint.Y > combo.ActualHeight) {
                UIElement popupContent = combo.FindChild<Popup>(null).Child;
                Point popupRelativePoint = Mouse.GetPosition(popupContent);
                if (popupRelativePoint.X < 0 || popupRelativePoint.Y < 0 || popupRelativePoint.X > popupContent.RenderSize.Width || popupRelativePoint.Y > popupContent.RenderSize.Height) {
                    combo.IsDropDownOpen = false;
                }
            }
        }
    }

You can look for FindChild<T>() implementations here.