The gridCount parameter indicates the number of grid columns occupied by the dialog box. The system divides the window width into equal regions. The number of equal regions is the number of grid columns, which varies by device. For example, if the screen density of a phone is between 320 vp and 600 vp, the number of grid columns is 4, and the valid value of gridCount is in the 1–4 range.
Reference
CustomDialogControllerOptions (including gridCount and other parameters)