How do you move a selection in GIMP across multiple layers?

You can't directly move a selection "across" multiple layers in GIMP. Instead, you need to move the content of the selection on each layer individually or in groups. Here's how:

Moving Selected Content on One or More Layers

1. Select the Layers: The first step is to select all the layers you want to move the selected content from. You can do this in a couple of ways:

   • Shift-Click: Hold down the Shift key and click on each layer you want to include in the Layers panel. This will select all the layers you click on between the first and last clicked layer.
   • Rubber-banding (Box Selection): Click in an empty area of the Layers panel above or below the layers you want to select. Drag the mouse to create a rectangular selection that encompasses all the target layers. When you release the mouse button, the layers within the box will be selected.

2. Make Your Selection: Use any of GIMP's selection tools (e.g., Rectangle Select, Ellipse Select, Lasso, or Free Select) to create the selection on your image. The selection is active on whichever layer is currently active (highlighted) in the Layers panel at the time of creation.

3. Move the Selection's Content:

   • Activate the Move Tool: Select the Move tool (usually the first icon in the toolbox, resembling a crosshair).

   • Configure the Move Tool: In the Move tool's options (usually below the toolbox), make sure the "Move the current layer" or "Move selected content" option is chosen, depending on what you wish to move. The "Move the current layer" option will move the entire layer, regardless of selection. "Move selected content" will only move what is inside the current selection on the active layer.

   • Drag and Move: Click inside the selection and drag to move the selected content. The content of the selection will move only on the currently active layer.

4. Repeat for Each Layer (If Necessary): If you have multiple layers selected, and you want to move the same selected content on each layer, you'll need to make sure that only one layer is active at a time (highlighted in the layers panel) and repeat step 3 for each individual layer. If you have linked the layers (by clicking between the eye icon and the layer thumbnail in the Layers panel), when you move content on one layer, the linked layers will move as well.

   Example Scenario

Let's say you have three layers: Layer 1 (a red circle), Layer 2 (a blue square), and Layer 3 (a green triangle). You want to move a rectangular selection containing parts of all three shapes.

1. Select Layers: Select Layer 1, Layer 2, and Layer 3 in the Layers panel using Shift-Click or rubber-banding.
2. Create Selection: Make a rectangular selection that covers part of the red circle, blue square, and green triangle.
3. Move Content on Layer 1: Ensure Layer 1 is the active (highlighted) layer. Use the Move tool (configured to move selected content) to drag the selection's content (part of the red circle).
4. Move Content on Layer 2: Click on Layer 2 in the Layers panel to make it active. Use the Move tool to drag the selection's content (part of the blue square). If you want the selection to be in the same location relative to what you moved in Layer 1, you'll have to position this selection manually.
5. Move Content on Layer 3: Repeat the process for Layer 3, moving the selection's content (part of the green triangle).

Important Considerations:

• Layer Order: The order of your layers in the Layers panel matters. If a layer is on top, it will obscure layers below it.
• Transparency: Selections are often used with transparency. If you delete content from a layer within a selection, you will reveal the layers below.
• Linking Layers: Linking layers can be useful for moving layers together. This is different from moving a selection, as linking moves the entire layers, not just the content within a selection.