Use the Lock feature in the LetterMat Dimensions section to lock the current size of the LetterMat to avoid adjusting it by mistake when dragging the mouse.
Click Unlock to Lockthe size of the current LetterMat.
Click Locked to Unlock the size of the current LetterMat.
Lock Object Size Definition
Use the Lock/Unlock feature to prevent the size of the opening from being changed by accidentally dragging the control corners with the mouse in Designer.