When you drag a speech bubble in SnagIt, if you click on the Bubble regardless of the shape there will a bounding box inside there will be a Grab box at each corner plus at center point on each side, and on the top and bottom. To compress height grab either the center point of bottom or top and drag up or down (depend on which point you grab). The height will reduce. If you grab point on either side and move the correct direction and length will reduce. if you grab a corner point and move diagonally the the entire shape will reduce or expand in both height and width the same amount in the direction you drag.