Dragging an image to a Collection in Lightroom

When in Library mode, if the 'Collections' menu on the left is closed (not currently displaying the collections), one cannot drag an image or images to the 'Collections' menu and hover to trigger the menu to open & show the collections and drop in these images. This is standard behaviour with such menus. Currently, we have to drop the image(s), go over to the 'Collections' menu , open it, then go back to the image(s) and place in the desired collection. What a bore. Would be grateful if you could fix this! Stephen