Bring Winforms control to front

Yeah, there's another way. The Controls.SetChildIndex() also changes Z-order. The one with index 0 is the one on top. Doesn't buy you anything though, BringToFront() uses this method.

Your SendLabelsToBack() method as given cannot work, it will also send the label to added to the back. But your next statement fixes that again.

Okay, that doesn't work, which means the BringToFront() method doesn't get executed. Look in the Output window for a "first chance exception" notification. As written, your SendLabelsToBack() will cause an exception if the user control contains any control other than a UserLabel. Also, set a breakpoint after the BringToFront() call and check the value of userContainer.Controls[0].Name when it breaks.

Controls' z-index is per-container.

If you call BringToFront on a control that is inside a container (such as a Panel), it will not bring the container to the front.
Therefore, the control will only go in front of other controls in that container.

To see what containers your controls are in, you can use the Document Outline pane in the View menu.

EDIT: Your userContainer control is probably behind a different control.