"Mandatory control"-indicator

The project I work in is in need of a way of visualizing that a field/control is mandatory or not.
Several approaches have been evaluated, and the preferred visual is a small triangular marker in the upper left corner (see attached JPG) inside the control. Why - well, the main reason is that this looks very much like the "mandatory" marker found on many paper-based forms. In the optimal case, the feature is controlled by a property "Is Mandatory" for the control.

The problem:
how to do this for the specified (see attached JPG) controls...

-...especially for UpDown-based controls and ComboBoxes (!)
We tried the same approach as described in the "Flat Controls" article at theCodeProject.com, but the text-part control overwrites any graphical parts we insert.

-...making it possible to run the target app in Win2k and (!) WinXP

-...without having to draw them completely from scratch ourselves?
(Of course, we would like to think that it is only a question of adding a routine that draws the indicator on top of the control, or under it(setting the control contents transparent) - in order to let the standard control behaviour and visuals appear normally in WIn2K and WinXP...)



Not-so-wanted approaches ;)
(We really _do_ want the triangular marker described above, and not...)
-use an outside-marker instead (e.g., an asterisk as in a web solution)
-use a surrounding frame with another colour (too intrusive)
-use another background colour (ditto)
-a label with different style/colour (visual focus on the wrong element)

Most grateful for any kind of answer/comment!

Best regards,
Mikael Ericsson