I've also changed how data is loaded when the sheet opens.
ISSUE FIXED. PLEASE REPORT ANY ISSUES IN SITE DISCUSSION
I'd recommend floorplanner.com for modern games. It's a quick and easy way to draw up basic...um...floorplans for your game. If I were using it for an online game, I'd probably import it into maptool or something like that so I could layer it and add tokens and stuff.