Flexible electronic device and method for controlling display of application execution screen

An electronic device comprising:

• a first housing;
• a second housing slidably coupled with respect to the first housing;
• a display in which a viewable area to a front surface of the electronic device is changeable from a first size having a first aspect ratio to a second size having a second aspect ratio according to a movement of the second housing with respect to the first housing;
• a memory storing computer-executable instructions;
• and
• a processor configured to access the memory and execute the computer-executable instructions, wherein execution of the computer-executable instructions by the processor causes the processor to perform a plurality of operations, the plurality of operations comprising:
• while the viewable area is maintained in the first size, in response to receiving a first input requesting a recent task list indicating at least one application currently running in background, displaying the recent task list comprising at least one execution screen image having the first aspect ratio and corresponding to the at least one application, wherein each of the at least one execution screen image having the first aspect ratio is an image captured at a time point when a corresponding one of the at least one application is switched from a foreground execution to a background execution;
• in response to changing the viewable area from the first size to the second size, updating the recent task list by generating at least one execution screen image having the second aspect ratio corresponding to the at least one application;
• and
• while the viewable area has is maintained in the second size, displaying the updated recent task list.