Currently (build 2143, but it was the same in past versions) when you highlight text you cannot copy it with ctrl+c until you release the mouse. Attempting to copy with the left mouse button still held down results in nothing being copied to the clipboard, so I frequently end up pasting the wrong thing (whatever was previously in the clipboard). I’m not sure if this is a bug or the intended behaviour, but certainly the standard behaviour (on Windows at least) is to copy the text that is currently highlighted.

Build 2143
Windows 7 64bit