if (IsDraggingDiagonal()) {

					/* Determine the "area" of the diagonal dragged selection.

					 * We assume the area is the number of tiles along the X

					 * edge and the number of tiles along the Y edge. However,

					 * multiplying these two numbers does not give the exact

					 * number of tiles; basically we are counting the black

					 * squares on a chess board and ignore the white ones to

					 * make the tile counts at the edges match up. There is no

					 * other way to make a proper count though.

					 *

					 * First convert to the rotated coordinate system. */

					int dist_x = TileX(t0) - TileX(t1);

					int dist_y = TileY(t0) - TileY(t1);

					int a_max = dist_x + dist_y;

					int b_max = dist_y - dist_x;

					/* Now determine the size along the edge, but due to the

					 * chess board principle this counts double. */

					a_max = abs(a_max + (a_max > 0 ? 2 : -2)) / 2;

					b_max = abs(b_max + (b_max > 0 ? 2 : -2)) / 2;

					/* We get a 1x1 on normal 2x1 rectangles, due to it being

					 * a seen as two sides. As the result for actual building

					 * will be the same as non-diagonal dragging revert to that

					 * behaviour to give it a more normally looking size. */

					if (a_max != 1 || b_max != 1) {

						dx = a_max;

						dy = b_max;

					}

				} else if (style & HT_RECT) {

				if (t0 != 1 || t1 != 1) {