Hi to all,
When a make a rectangle, fill it with colour and without borders, and duplicate and then put the two rectangles next to each other and align and group them, there is still a visual lign between the two rectangles.
How can I make this lign disappear? Hope you can help me.
Thanks, Rubins

I'm not sure it's a bug.

Anyway, I've repported it here

Welcome rubins!

Yes, it's a known bug. It has to do with how Inkscape displays things. There are a couple of workarounds. But first I want to make sure that we're talking about the same thing. Could you post a screenshot of the problem?

Workarounds include slightly overlapping the rectangles, and a filter that helps cover it up, called Stitch. You can find it in this topic with instructions for using it: viewtopic.php?f=5&t=9034&p=33279&hilit=stitch#p32882

Make sure the rectangles snap to the pixel grid, and when exporting use the Inkscape default 90 dpi. Read more about it in Inkscape FAQ.

prkos wrote:Make sure the rectangles snap to the pixel grid (…)

This doesn't fully prevent the small gaps due to the anti-aliased rendering (on-canvas) of vector shapes against a transparent or differently colored background. The visibility of the gaps depends on the zoom level (they disappear for pixel-aligned vertical/horizontal edges at zoom level 100%, but reappear when zooming in or out). AFAICT the issue persists even with the new cairo-renderer in current development snapshots.

[Edit]
Related FAQ entry:
I have two adjacent objects with their edges abutting precisely, but at some zoom levels, a seam is still visible.
[/Edit]

Thank you all very much for the welcome and your help.
I'm going to work with it, and I will tell you the result.

~suv wrote:they disappear for pixel-aligned vertical/horizontal edges at zoom level 100%, but reappear when zooming in or out

I am using a recent dev build windows xp, and after some experimentation the seam between two aligned objects disappears for zoom percentages that are a multiple of 5! Can someone confirm this? I was also wondering if this means that exports at some particular resolutions might not show this seam...

Later...
A possible solution! At least on windows xp, with a recent build...

Onscreen zooms of multiples of 5, as i said previously, display without the seam Well and good, but flawless bitmap export is what we really after... Well, at least I am...

So... I tried exporting with various resolutions with no luck, until - yes! 96 DPI! no seam! All multiples of 96! No seam! 48! No seam! 12! All multiples of 12! No seam!
Well, I could go on, but after all the dust settled the net result was that:

Any bitmap exported at a DPI of any multiple of 3 resulted in a seamless PNG!

Of course I would like someone to confirm this but for right now it looks like a working answer.

Wow, druban, that's good work!
I don't have time to test right now, but I'm just impressed with your tenacity

Hmm, I thought there was more interest in this bug than appears to be the case.
I am still looking for a confirmation for the workaround, so anyone who was having trouble with the antialiased gap, could you see if this works for you, especially in the official release (0.48.1), and on platforms other than Windows?

druban, to encourage more discussion, perhaps you could start a new topic in Inkscape Ideas, or Software Issues. I'm not sure which forum would be best, probably Software Issues? But I do think this deserves more attention! (topic title here will probably allow it to die away)