Fixing issues with --use-clipboard option

Author: phase1geo

src/Application.vala

@@ -68,10 +68,12 @@ public class Annotator : Gtk.Application {
         Process.exit( 1 );
       }
     } else if( use_clipboard ) {
-      if( !appwin.do_paste_image() ) {
-        stderr.printf( _( "\nERROR:  Image does not exist on the clipboard\n" ) );
-        Process.exit( 1 );
-      }
+      AnnotatorClipboard.get_clipboard().changed.connect(() => {
+        if( !appwin.do_paste_image() ) {
+          stderr.printf( _( "\nERROR:  Image does not exist on the clipboard\n" ) );
+          Process.exit( 1 );
+        }
+      });
     } else if( take_screenshot ) {
       appwin.do_screenshot();
     }