[ EXEC <command> | RUN <command> | ScreenRun <screen> <cmd> 
	 | UPDATE | LOADUPDATE | LOAD <file> [arguments]             
	 | EXIT [<string>] | QUIT [<string>]                         
	 | DumpX <variable> | DumpY <variable>                       
	 | LastX <variable> | LastY <variable>                       
	 | LastXPos <variable> | LastYPos <variable>                 
	 | Popup | PopupClose                                        
	 | Setenv <variable> <value> | UnSetenv <variable> ]         
	 ( ['command 1' 'command 2' ... 'command n'] )               


 SETENV variable "value"
 Sets the env variable <variable> to "value".
 
 These two buttons works in the same way:
 button Hello setenv var hello
 button Hello exec "setenv var hello"
 
 But the last one uses the external AmigaDos command "setenv".
 

 UNSETENV variable
 Deletes the env variable <variable>.