Interaction with the block instances in the Block Wiring tab is similar to that in the Event Flow tab.

Click on a block instance rectangle to select it. The rectangle's border will become bold red and eight drag handles will appear around the rectangle.

To move a rectangle simply press and hold the left mouse button while pointing to it, and drag to the desired location. Release the mouse button to confirm the new location.

You can use the drag rectangles to resize the rectangle in any of the eight coordinates. As above, point to a drag handle, press the left mouse button and hold down while dragging the handle to the desired location. If you hold down the Shift key while dragging, you will restore and then preserve the rectangle's aspect ratio.