For the calendar: I reconize my calendar in your screenshot

. You should do this to to change the calendars icon:
-Right click the calendar icon
-A menu will popup, click on "dock item properties..."
-A dialog will popup, locate the button which says "skins" and click it
-A new dialog will popup. In the list choose the skin you want and click on the "Apply this skin" button.
- Click on OK, the skins-dialog will disappear and close the Appointments-dialog.
-That was all