Change text style is removing <br/> tag

I am using CKEDITOR 3.6.4. I have made a plugin to change font style (don't want to use 'stylesheetparser' as I want to change style by one-click only)

exec : function( editor )
	{ 
               var style = new CKEDITOR.style(
                     { styles: { 'color': 'Purple','text-decoration':'underline'  }}); 
               style.apply(editor.document); 
         }

It works, but if I select  text that include the last char of the line,  it remove the line-break in text , then join 2 lines together....

become

Any suggestion to fix this?Thx~~