ListBox Header Height

rgb

Seem have 32px height, correct ?

Value usual for use in MouseDown for calc what row are clicked when header are visible

Need to know this value before event SelectionChanged

Great have this information in constant in system class or listbox
If header height change in future, not good have hardcoded value

Garry

The header is currently approximately 32 logical points high, but that is a theme-dependent implementation detail and shouldn’t be hard-coded.

I’ve implemented a more reliable solution:

Function ListBox.RowAtPoint(x As Double, y As Double) As Integer

It returns the displayed row under the supplied ListBox-relative coordinates, or -1 when the point is over the header, a scrollbar, blank space, or outside a visible row.

Property pressedRow As Integer = -1

Sub ListBox1_MouseDown(x As Double, y As Double, button As MouseButton)
    pressedRow = Me.RowAtPoint(x, y)
End Sub

Sub ListBox1_SelectionChanged()
    If pressedRow >= 0 Then
        Print("Pressed row: " + pressedRow.ToString())
    End If
End Sub

The coordinates from MouseDown can be passed directly to RowAtPoint; it automatically accounts for the header, scrolling, and the ListBox’s position inside its window or container.

For pointer-driven selection, MouseDown will also be delivered before SelectionChanged, allowing this pattern to work reliably. This will be available in the next Studio update: https://feedback.objo.dev/feature/1312