Fix bug where if you selected something then left clicked you would lose the selection buffer.

now when you left click it checks to see if there is text selected

source/blender/src/drawtext.c

@@ -1531,9 +1531,11 @@ void winqreadtextspace(ScrArea *sa, void *spacedata, BWinEvent *evt)
 				do_textscroll(st, 2);
 			} else {
 				do_selection(st, G.qual&LR_SHIFTKEY);
-				buffer = txt_sel_to_buf(text);
-				putClipboard((GHOST_TInt8*)buffer, 1);
-				MEM_freeN(buffer);
+				if (txt_has_sel(text)) {
+					buffer = txt_sel_to_buf(text);
+					putClipboard((GHOST_TInt8*)buffer, 1);
+					MEM_freeN(buffer);
+				}
 				do_draw= 1;
 			}
 		}