Information processor for changing scroll amount upon receiving touch operation performed on return key or forward key

An information processor comprising:

• a display device;
• a touch panel;
• a storage device;
• and
• a control device including a processor, and as a result of execution of a control program by the processor, functioning as a controller
• causing the display device to display, in a predefined region, a portion in a predefined direction of a predefined image as a display portion and also to display:
• a forward key configured to input an instruction for displaying, in the predefined region, a forward image portion being located on a side of a first direction directed more closely to one end side of the predefined direction than the display portion and continuing to the display portion in the predefined image;
• and a return key configured to input an instruction for displaying, in the predefined region, a return image portion being located on a side of a second direction directed more closely to another end side of the predefined direction than the display portion and continuing to the display portion in the predefined image,
• causing the display device to, upon receiving slide operation performed on the display portion via the touch panel, scroll the predefined image in the predefined direction toward a direction of the slide operation until a movement amount of the predefined image from a time point at which the slide operation was received reaches a scroll amount set in accordance with an attribute of the slide operation and causing the storage device to store the set scroll amount as an additional scroll amount, and
• upon receiving touch operation performed on the forward key via the touch panel before the movement amount of the predefined image from the time point at which the slide operation was received reaches the set scroll amount, adding the additional scroll amount to the set scroll amount to change the set scroll amount and causing the display device to scroll the predefined image in the predefined direction toward the first direction until the movement amount of the predefined image from the time point at which the slide operation was received reaches the scroll amount having been changed.