Abstract: A computer system includes a mouse and a computer for selecting a left-handed mode and a right-handed mode as a current operation mode of the mouse. When a right hand operates the mouse, the mouse automatically generates a first mode-setting signal, and the computer shifts the current operation mode to the right-handed mode according to the first mode-setting signal. When a left hand operates the mouse, the mouse automatically generates a second mode-setting signal different from the first mode-setting signal, and the computer shifts the current operation mode to the left-handed mode according to the second mode-setting signal.

Abstract: The present invention provides a change-oriented method for organizing electronic spreadsheet data, comprising: saving the contents of the cells in the electronic spreadsheet and valid updates into the same electronic spreadsheet document, wherein the valid updates comprise the updates to the contents of the cells and the time information associated with these updates. With the invention, every valid update of a cell comprising the time information can be recorded in the electronic spreadsheet document, so as to provide a basis for applications of electronic spreadsheets, such as taking a snapshot, obtaining a chart of the historical information and so on. In addition, the present invention also provides a method for taking a snapshot of an electronic spreadsheet document at a given time, a method for obtaining the historical information of an electronic spreadsheet document in a given time period and a change-oriented electronic spreadsheet system.