Yep, I think native scrollbars is reasonable for DGXL. Maybe eventually you’ll sniff whether scrollbars take space and draw your own that match the size if they do, but it’s definitely a little risky.
These sorts of things are particularly interesting once you support a sparse spreadsheet; drawing your own scrollbars becomes much more compelling then, so that you can make them more useful. No idea about Excel, but LibreOffice Calc—(which amusingly gets scrolling by precise touchpad wrong in just the same way as Luckysheet, sans the wrong horizontal direction; this stuff is hard everywhere)—well, LibreOffice Calc’s scrollbars essentially pretend the whole time that the document is only as large as the extent of the cells with content or the selection, whichever is larger in each axis, plus a screenful or so in each axis. So if you’re at A1 of an empty document, the scrollbars thumbs fill about half of the bar, but if you’re at AMJ1048576 (maximum sheet dimensions are 2¹⁰×2²⁰), the thumbs are tiny at the bottom and right.
Sounds like a very strange approach, those LibreOffice Calc scrollbars ;-) Sometimes it's useful to give a minimal width/height for a scrollbar thumb, so that it remains visible and selectable. A tiny scrollbar thumb might be "realistic" when it represent the viewport vs document dimension, but it always looks a bit stupid.
How come you know so much about scroll bars? Did you make your own spreadsheet app/component?
The spreadsheet approach makes a lot of sense: they’re dealing with what’s practically a near-infinite document (a million cells is close enough to infinity in such cases!), but people seldom actually use that many cells. Thus, the shenanigans they pull are to make the scrollbars useful, so that they typically give a fair reflection of the actual size of the document the user is dealing with. I imagine Excel does something similar.
I know so much mostly just because I observe carefully, in both desktop and web software. I haven’t implemented anything like this, but when I observe things imperfect on the web and it’s a type of imperfection I’m not familiar with, I often assess it to figure out whether it’s possible to get right. I also value getting things right in straight HTML/CSS with no JavaScript.
These sorts of things are particularly interesting once you support a sparse spreadsheet; drawing your own scrollbars becomes much more compelling then, so that you can make them more useful. No idea about Excel, but LibreOffice Calc—(which amusingly gets scrolling by precise touchpad wrong in just the same way as Luckysheet, sans the wrong horizontal direction; this stuff is hard everywhere)—well, LibreOffice Calc’s scrollbars essentially pretend the whole time that the document is only as large as the extent of the cells with content or the selection, whichever is larger in each axis, plus a screenful or so in each axis. So if you’re at A1 of an empty document, the scrollbars thumbs fill about half of the bar, but if you’re at AMJ1048576 (maximum sheet dimensions are 2¹⁰×2²⁰), the thumbs are tiny at the bottom and right.