Hi, I suppose you are trying to use SaveCtrlBitmapToFile () function. This function accepts a pathname as an input, so you can set exactly where to save the image.
In case you want to give your customer a full navigate-and-select functionality you can add FileSelectPopup before saving the control. FileSelectPopup permits the user to navigate and select/write a filename. Provided that you choose "Save" as the button label, this function also checks for duplicates and emits the standard "File exist: cancel / overwrite" popup message. The pathname returned from this function can then be passed to SaveCtrlBitmapToFile function.