I am really used to thinking of 0, 0 as the origin of a coordinate system, and working with slopes and lines and objects in relation to the origin. It sometimes seems really dumb to have the top left corner of the document represented by 0, 0 because then anything centered on the coordinate system such as a complex bolt circle has only one quadrant on the document page. Meh. We should be able to use the center of the page as the center of the coordinate system, home, origin, whatever you want to call it, at least as an option. I am sure someone has figured out a way to do this. 

What I have been doing is simply setting the desktop color in Inkscape to ffffffff, and disabling page border, then simply drawing my part relative to 0, 0 and then if I want to export something to view or share outside of Inkscape or print a part, I just select all and the import selected. It then exports with the copy's coordinates based on the upper left corner of the pasted features, but that's okay since it is not a working copy, just a show and tell or for printing. Still, it would be nice if I could skip all that kludgery by setting the center of the coordinate system to the center of the document. Any suggestions? Besides "don't use Inkscape for whatever you are doing, it is just for making little mermaids and smiling frogs and fairy princesses and and daisies with faces in the middle or unicorns" or similar. I am using Inkscape and I will continue to do so until it is no longer possible to do so. Thanks in advance for any help.

Yes, you can set the origin to the center of the page in Inkscape by manually adjusting the grid and guidelines. Go to "Document Properties" (Shift+Ctrl+D), set the "X" and "Y" origin to half the width and height of your page. This will shift the origin to the center, making it easier to work with symmetrical designs and complex bolt circles.

maverick 
"Go to "Document Properties" (Shift+Ctrl+D), set the "X" and "Y" origin to half the width and height of your page."

Just click the small circle on the "align to page" in the grid dialog and x,y will automatically be set to center of page. 

However, I don't think this is what Growley is refering to. The x,y cordinates of an object will always be referenced to either the top left corner or bottom left corner depending on your preferences. He wants to be able to set the origin to 0,0 dead center of the page. If he creates an object at 0,0 at center of page and moves it left, he wants x to go negative. Go right and x will go positive. 

Exactly. Origin is (0, 0) in a rectangular coordinate system and that's what I would prefer to have in the center of the page. That is the convention, in geometry and mathematics, because obviously you must deal with negative numbers, and not just ignore them. 

Luckily Inkscape doesn't care if I go "out of bounds" and so with border disabled, and desktop color set to same as document background color (ffffffff) I can just use the whole window as my page, and center the origin in the window and draw as if 0, 0 is the center of the world, as it should be. In reality, only the lower right quadrant will be on the page if I save the file, but for printing or viewing outside of Inkscape, I can enable border and then select all, and move everything onto the page. Or do what I have been doing and saving the working file as is, with everything centered about (o, o). Then, to export or print, I just select all objects and it will save or print with the entire drawing on the page. But I would like to not have to do all that. 

It seems like an arbitrary choice, but the svg standard is designed for displaying vector images in a web page, not for geometry or CAD. Since web pages are (generally) oriented top-down and left-to-right, it's logical to place the origin at the top-left corner.

I can't imagine that this is easy to change. All of Inkscape's wizardry has for many, many years been developed around this coordinate system. You'll have to stick with your workarounds.

Paddy - should also be noted that Inkscape MUST follow the SVG specifications specified by the world wide web consortium. Something I keep forgetting because Inkscape developers have pushed the envelope as to what Inkscape can do but still follow the specification as much as possible.