REPLY IN RUSSIAN! See attached sample with 1 line of code. I NEED JUST AN ADVICE, I NEED ANSWER: 1. Why is that? 2. How I can avoid this? Solution? Details: There is two GroupBoxes one over another. My code makes the first one (located under) invisible. Question: why the second one becomes also invisible while executing the code? If you'll move second GroupBox a little up or left it will be visible, as expected. But if its located on the same coordinates as the first one (invisible) - both comes invisible. WHY? SOLUTION? Probably the same happens to Panel control!