An information processing device comprising: a memory (11b, c, d) configured to store pieces of attribute data; a display; a processor (11, 11a) configured to: retrieve first attribute data stored in the memory in association with a first running application program; retrieve second attribute data stored in the memory, wherein the first and second attribute data are indicative of a category of an application program and wherein the second attribute data is set by a user and changes according to one of a time and a location of the information processing device; identify a first window corresponding to the first running application program, which is displayed on the display; identify a second window overlapping with the first window, which is displayed on the display; if the first attribute data and the second attribute data are identical, set priority levels for the first window and the second window so that a priority level for the first window is higher than a priority level for the second window; and cause the display to display the first window whose priority level is higher, ahead of the second window whose priority level is lower. a memory (11b, c, d) configured to store pieces of attribute data; a display; a processor (11, 11a) configured to: retrieve first attribute data stored in the memory in association with a first running application program; retrieve second attribute data stored in the memory, wherein the first and second attribute data are indicative of a category of an application program and wherein the second attribute data is set by a user and changes according to one of a time and a location of the information processing device; identify a first window corresponding to the first running application program, which is displayed on the display; identify a second window overlapping with the first window, which is displayed on the display; if the first attribute data and the second attribute data are identical, set priority levels for the first window and the second window so that a priority level for the first window is higher than a priority level for the second window; and cause the display to display the first window whose priority level is higher, ahead of the second window whose priority level is lower. retrieve first attribute data stored in the memory in association with a first running application program; retrieve second attribute data stored in the memory, wherein the first and second attribute data are indicative of a category of an application program and wherein the second attribute data is set by a user and changes according to one of a time and a location of the information processing device; identify a first window corresponding to the first running application program, which is displayed on the display; identify a second window overlapping with the first window, which is displayed on the display; if the first attribute data and the second attribute data are identical, set priority levels for the first window and the second window so that a priority level for the first window is higher than a priority level for the second window; and cause the display to display the first window whose priority level is higher, ahead of the second window whose priority level is lower.