Hi,
It is the "ButtonRegionBackground". Like the standard Window MessageBox, the region where the button "OK" is located has it's own background. Just set this "RegionBackground" to the same color as the "Background" property of the MessageBox.
It is the "ButtonRegionBackground". Like the standard Window MessageBox, the region where the button "OK" is located has it's own background. Just set this "RegionBackground" to the same color as the "Background" property of the MessageBox.