The GridLayout property specifies how thumbnails are arranged when the Mode property is set to exThumbnailGrid (the default mode). It defines a horizontal or vertical layout using the format "columns x rows" (for example, "1 x" for fit-to-width or "x 2" for fit-to-height), effectively enabling a columns × rows arrangement.

The GridLayout property behavior is:

• Empty (default): The control automatically determines the best layout based on its size. If the control is wider than it is tall, thumbnails are arranged in rows with horizontal scrolling. If the control is taller than it is wide, thumbnails are arranged in columns with vertical scrolling
• Columns × ("m x"): Fixes the number of columns to m. Thumbnails are arranged vertically and scroll vertically when more thumbnails exist than fit
• Rows × ("x n"): Fixes the number of rows to n. Thumbnails are arranged horizontally and scroll horizontally when more thumbnails exist than fit
• Columns × Rows ("m x n"): Both columns and rows are specified. The control chooses the scroll direction based on its aspect ratio. If wider than tall, columns are fixed and scrolling is horizontal. If taller than wide, rows are fixed and scrolling is vertical

The ThumbnailMinWidth, ThumbnailMinHeight, and related properties control the size of the thumbnails when the exThumbnailAutoFit flag is not included in the Mode property.

For example:

• "1 x" displays a single column of thumbnails. If more thumbnails are available, they are arranged vertically, and the user can scroll vertically
• "x 2" displays two rows of thumbnails; additional thumbnails are arranged horizontally, requiring horizontal scrolling