IF your picture has multiple layers (it may not - jpeg's don't when brought in)
it will allow you to determine which layer is being modified by the editor,
and to rearrange which layers are on top.
Press control + L to open the Layers window.
In the "Layers, Channels, etc" window, right click on a layer and click delete.
Press Control + L to re-open the Layers window
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.
Click on windows / dockable dialogs / layers channels paths
Drag the whole file from a windows explorer window to the GIMP page then use the move tool.
Once upon a time you could drop an image into GIMP and start working on it. No more. Now, you must open it through the application. You do this with Ctrl+o for as many images from a single folder as you can handle, or Ctrl+Shift+o to open them all as layers in a single window.
There's a specific command for that under 'layers'. You can also do it in the layers "toolbox" (wrong term- but the stuff on the right side of the screen)
In GIMP, to draw on multiple layers simultaneously, you can use the "Paint on All Layers" option. First, select the layer you want to draw on, then go to the "Tool Options" for your brush or pencil tool and check the "Paint on All Layers" box. This allows you to apply your strokes to all visible layers at once. Remember to ensure that the layers you want to affect are visible and not locked.
Right-click on Gimp in your Applications folder and select "Open With". This will open a window of all your applications and you'll select X11. X11 is under Utilities. I'm not sure how you managed to make Gimp open with Photobooth, but kudos to you haha.
Open the Layers window.
To superimpose pictures in GIMP, open both images in separate layers, adjust the opacity of the top layer to see both images, and use the Move Tool to position and align them as desired.