Drag horiozontal and vertical guidelines through the exact center of the two squares. Using the Pen Tool, draw a horizontal line through the center of both squares as shown. Copy the line to the clipboard (Ctrl-C). Select the horizontal line and the small square and from the Arrange menu select Combine Shapes--Subtract Shapes. Select the small square and from the Arrange menu, select Break Shapes. Paste the horizontal line using Shift - Ctrl - V to paste the line in the exact same position. Repeat the process on the larger square. Be sure to break it apart.
Draw a vertical line though the center of the two squares and repeat the process to break the squares into four sections as shown. Notice that the conical fill remains intact. Ask your friends who use CorelDRAW if they can do this. (They can't!).