[RESOLVED] Content listbox not visible with Windows 7

[HermanTabbert]

I make programs on a computer with Windows XP.
I am testing the programs also on a computer with Windows 7 Pro.
99% works fine on both computers.
However, one form gives a problem i cannot solve so far.
Before saving data it will be controlled and the errors c.q. the missing fields are shown in a listbox on the form and 2 cmd-buttons.
On the Windows XP Machine it looks:
See windowsXP.jpg and on the Windows 7 machine see:
Windows7.jpg
When i click with the mouse on a line in the windows7-box the line becomes visible. When i print the form it is all good.
Also when i click an (invisible) commandbutton it becoms visible and response.
Please help.
Herman