Want to simulate the mouse drag and drop event, perhaps only like a human to operate? Open the Explorer, or add an Explorer control on the VB6 software to display a PNG file, and then click the file, and then drag and drop to another process.
The process may display a WEBVIEW2 web control that accepts file drag-and-drop events in parts of the page.
Analog mouse operation, will occupy the entire computer, it can not work normally.