When you select Autosize Window, Extra! adjusts the display window size to best fit the current font. This eliminates extra margin spacing around the text once a font is established.
To size your 3270 session window automatically
From the Options menu, choose Settings.
From the Categories List, select Font.
From the General page, select the Auto Size Window to Font Size check box.
Choose the OK or Apply button.
If you do not want the display window to resize automatically, clear the Auto Size Window to Font Size check box.