Why are the Tooltips not being shown on a NumericUpDown control?

This is because of a bug in the .net framework. When tooltips are set on a control that hosts other controls within it (like the numeric updown), tooltips are not shown on those child controls.

To workaround this issue, do the following in code:

[C#]
foreach(Control c in this.numericUpDown1.Controls)
{
	this.tooltip.SetToolTip(c, 'mytooltip');
}

[VB.Net]
Dim c As Control
For Each c In Me.numericUpDown1.Controls
	Me.tooltip.SetToolTip(c, 'mytooltip')
Next