Sets the Focus to the InstrumentTrackWindow if a preset or a sample droped to it.

src/tracks/InstrumentTrack.cpp

@@ -1505,6 +1505,7 @@ void InstrumentTrackWindow::dropEvent( QDropEvent* event )
 		engine::getSong()->setModified();
 
 		event->accept();
+		setFocus();
 	}
 	else if( type == "presetfile" )
 	{
@@ -1516,6 +1517,7 @@ void InstrumentTrackWindow::dropEvent( QDropEvent* event )
 		engine::getSong()->setModified();
 
 		event->accept();
+		setFocus();
 	}
 	else if( type == "pluginpresetfile" )
 	{
@@ -1530,6 +1532,7 @@ void InstrumentTrackWindow::dropEvent( QDropEvent* event )
 		i->loadFile( value );
 
 		event->accept();
+		setFocus();
 	}
 }