I create a tPanel in a form of a Delphi application. Through a dll an external program is filling the panel with data (drawing a picture).
So far so good. The data is visible.
But only if I didn't 'touch' the panel before. If I set the panel visible or changed the top, left, width, ... values then the panel is filled with the data of the external program - but directly after that the data will be 'deleted?'. And the look of the panel is the same again as it was before the data were transferred.
Where could be the problem? Why does Delphi allow to draw a picture on the panel in the first case but in the second case it overwrote all again?