To be clear - are you referring to Qlik Sense Desktop or the full Qlik Sense platform?
I assume you mean like a CTRL+R - similar to QlikView?
What I do - is open up two tabs.
One that shows the Data Load Editor and one that shows my sheet. That way I just switch back between the two - regardless if it is the Desktop Tabs - or the browser tabs - depending on which product you are working in.
Some additional keyboard shortcuts and gestures are available here, I will see if CTRL+R will make its way in the product and update you.