If you have used Marquee tool to made any selection, you can deselect by pressing Ctrl D, or you can go to the paths palette and click on the empty space if it is made up of shape layer.
If you create a new Photoshop file, by default the background (locked) layer will be selection. You cannot deselect this layer, to do that you have to convert to
regular layer. But if your layers palette is filled layers and there is no empty space to click, how do you deselect a layer?
01. Assume this is your workspace and you cannot increase the height of the layers palette anymore than this.
(fig 1.0)
02. To deselect the layer generally you click on an empty space in the layers palette.
But what happen if you do not have any empty spaces and you cannot extend the layers palette anymore than the Photoshop workspace.
(fig 2.0)
03. Other panels like Brush, Brush Preset, Swatches will automatically create a new column if you expand the width. But that will not work in layers.
Even if you have a separate monitor for Layers palette, you are still stuck with the same height.
(fig 3.0)
04. One way is to change the Thumbnail Size to 'None', this will make the thumbnail in the layers palette to smaller size and you could get some extra space if your layers went little
beyond the layers palette.
(fig 4.0)
05. To deselect the layer, go to Select > Deselect Layers. This will deselect any layer in the layers palette.
You can also use the keyboard shortcut, hold the Ctrl and click on the selected layer. If you click on any other layer holding the Ctrl key will make a multiple selection, like
holding a shift and selecting.
Since this is related to selection i guess thats why they kept it under Select menu and not Layer menu.
(fig 5.0)
