Down at the bottom of the screen, where the icons are, click there and “tile” the open icons. That will “hold” the mail and other folders open so you can “drag and drop”.
Alt & Tab keys ?
1) Once you are left clicking and dragging picture, etc... Go with your Mouse to the bottom of your desktop, while still holding your pic, etc...
2) That is where all your open Icons are located. Find it, hover Mouse over it and it should pop up. Then release it by letting go of your left button.
Hope this helps.