Operating method for multiple windows and electronic device supporting the same

An electronic device, comprising:

• a display displaying multi windows;
• and
• a processor functionally connected to the display,
• wherein the processor is configured to:
• display a first screen corresponding to a first application in a first window of the display;
• display a second screen corresponding to a second application in a second window of the display;
• enlarge the first window to display a third screen including an additional region that has been hidden by a size of the first screen and reduce the second window to display a fourth screen in which graphic objects output on the second screen are reduced, as a position of a boundary line is changed in response to a first user input for moving the boundary line between the first window and the second window in a first direction, when receiving the first user input;
• and
• reduce the first window to output a fifth screen including only a part of the first screen and enlarge the second window to display a sixth screen in which the graphic object is enlarged on the second screen, as the position of the boundary line is changed in response to a second user input for moving the boundary line between the first window and the second window in a second direction different from the first direction, when receiving the second user input,
• wherein the processor is configured to perform a control to generate the third screen by adding a new graphic object at a position spaced apart from the boundary line of the first screen by a predetermined distance.