When you right click (or Ctrl+Click) over specific layer of the image in the main window, you will activate context popup menu.

First item of this menu displays small preview of the image embedded in the layer and some additional information: image file name, angle of layer rotation, number of the image in mosaic library.

Second and third options of the popup menu are Bring Layer to Front and Send Layer to Back.

Next options are depend from

Open Library Button.

Show Candidates check box at the left of the main screen.

When Show Candidates is ticked you will see a list of image previews for most suitable pictures from currently opened library for replacing the current tile.

Note: Candidate list are visible only if Photo Jumble Library is open.

If you disable Show Candidates check box you'll get these options:

Straighten Layer - This will set rotation angle of the layer to zero.

Remove Image - It will removes the images from the layer and will replace it with semitransparent placeholder filling.

Duplicate Layer - This will add a new layer with same size, position and picture as the layer over which you activated Popup menu.