Rename for clarity
Rename for clarity

@pkerpedjiev I hope this resolves the semantic issue. You might find `graphics.clear` in the first if clause more intuitive but that's not the only place the graphics object has to be cleared. If this is still confusing please propose a better name or how you would like to see `graphics.clear()` being called from the blur and app.mouseLeave events. Note that arrow functions as the event handler will result in memory leaks as they are not unsubscribale, hence `() => graphics.clear()` doesn't work.

hms-dbmi/higlass,hms-dbmi/4DN_matrix-viewer,hms-dbmi/higlass,hms-dbmi/4DN_matrix-viewer,hms-dbmi/4DN_matrix-viewer,hms-dbmi/higlass,hms-dbmi/higlass