Please! .. let us (slowly) change this to 8-space indent for line wrap!  
* The code is much more easy to read. Since we have the braces at the and of the line, you can instantly distinguish between a line wrap and a conditional code block.  See  "src/control/control.cpp @@ -49,7 +49,7 @@"  below. 

Here what other think: 
* it is the default K&R Style of Eclipse to wrap lines with 2 x indentation. 
* It is part of http://google-styleguide.googlecode.com/svn/trunk/cppguide.xml#Function_Calls
** They wrap at the function parentheses or at 2 x default indention (2) -> 2 x 2 = 4
* The function parentheses wrap is part of th Mixxx style guide as well, but it is not suitable in any cases, eg. when the function parentheses is already near the line end like in the sample above. 
* The same for line wrap in Function declarations http://google-styleguide.googlecode.com/svn/trunk/cppguide.xml#Function_Declarations_and_Definitions