If you want to prevent resizing of both columns and rows, call the SSSetUserResize function and set the wUserResize parameter to 0.
If you want to prevent resizing of all columns, call the SSSetUserResize function and set the wUserResize parameter to either 0 (neither columns nor rows can be resized) or SS_USERRESIZE_ROW (only rows can be resized).
If you want to prevent resizing of a specific column, call the SSSetUserResizeCol function.
If you want to prevent resizing of all rows, call the SSSetUserResize function and set the wUserResize parameter to either 0 (neither columns nor rows can be resized) or SS_USERRESIZE_COL (only columns can be resized).
If you want to prevent resizing of a specific row, call the SSSetUserResizeRow function.