How do you put dropable dialogs back into a GIMP toolbox?

I actually wondered this for a while when I updated my GIMP before figuring this one out. I tried dragging the entire window and dropping it, but that obviously didn't work. Then I tried grabbing just inside the window and dragging that.

Let's take the dialogue box "Layers" for example. The entire window is, in my case, surrounded by a blue border (I use Windows, obviously) telling me that this window is active. Instead of grabbing the blue border, I grab the word "Layers" at the top and drag it into GIMP where it says "You can drop dock-able dialogues here".

To add more dialogues to my GIMP toolbox, I drag the dialogue to the raised bar that separates my GIMP toolbox and my other docked dialogues.

I hope I've explained this well enough. If something is still hazy, please feel free to ask. Good luck.