Direction control in Merge Graph Windows, Merge Graphs to Layout, Arrange Layers, and Layer Management dialogs.

Example 1: When merging 6 graphs into a multi-panel graph, e.g. 2 x 3, there is now an option to specify arranging horizontally first or vertically first.

Example 2: Suppose there is a 2 x 3 panel graph which was arranged horizontally first. Choose Graph: Arrange Layers… to switch the number of rows and columns to 3 x 2 and Direction: Vertical First—the panels will be transposed.