When you have a lot of objects that you want to select, the easiest way to select them is to do mouse area drag selection. But this function is inconsistent / sometimes not working when you have a colored background/artboard (Created from shapes). I tried to turn off the color of the background and just enable stroke, but if the size of your board is big, the stroke becomes so thin that is not visible. And there’s no way to make the stroke thicker. Thank you.
One workaround that I found is to select one object first, then do the mouse drag selection to select the rest of the object.