When editing an article, select a flash marker. Select a part of text by mouse and both the background color and the text color will be changed into the selected flash marker's color.  

 

Click "Main Menu->Tools->Flash marker 1/2/3" successively so as to select the corresponding flash marker.  Re-click the selected menu item of the flash marker so as to cancel the seleted flash marker.  

Flash marker has XOR property.  When you apply the flash marker again on the text that has already changed the color by the flash marker, the changed text and background colors will be canceled.