Is there a way to edit a pattern (modify its paths, objects, colors, etc...) without having to make a new one and cluttering the pattern list, and also in order to have all objects using this same pattern be updated with proper scaling and rotation (which can not be achieved by selecting the objects and selecting a different pattern in the "Fill" tab) ?

I can do it in the XML editor but it's all textual, so I can't edit complex patterns.

Hi.

You can group objects, clone them and convert a clone of the group to a pattern.
Preferably draw a rectangle first of the desired tile size, group it, clone it and convert the clone to a pattern.

This way you can add any new element to the tile, and scale/rotate them etc.
Only specifying a new tile size is not possible, because the original object's bounding box is used and you cannot update that (-other than in the xml editor? Haven't tried.).
But by that trick of using a rectangle first you can avoid clipping the group first -resulting in buggy rendering in many cases.

Just wrote the same - now not

Thanks. That's not very handy though, since I like to scale and rotate my patterns.

Then use the transformation panek (Shift+Ctrl+M).

First select same/fill color, then scale/rotate everything in the selection, while keeping the scale pattern with object option toggled in,
then reverse the transformation without scaling the pattern.

Wait, I just understood what you said in your first reply.
I tried it and it does pretty much what I want, but it's quite buggy.
If I update the original, the changes don't appear on the pattern unless I move the Pattern object. And that only works the first time. If I update the original once again, the changes don't appear even if I move the pattern object anymore.
I have to save and revert the file, which on 0.92 happens to crash most of the times (I made a bug report about this).

Check this for an example.

It will update when you zoom, or do any other action, I think. You're right that the pattern doesn't update right away.

woops, I re-wrote my previous post while you replied. You should re-read it.
It seems to work better with your file though. I don't need to revert.

Transformations may mess up the cloning.
Better start with a clean file or manage to have no unnecessary transformations added -like added by resizing page to content etc.
Not quite sure about the options, in 0.92 there were some changes added.

I recently wrote a long explanation how to edit a pattern, but I can't find it now. So I'll write again. This is a way to scale, move and rotate the pattern, without having to draw it again but slightly differently. However, if you need to edit the paths, delete parts, add new parts, then what the others wrote works.

Although, as far as cluttering up the file with a lot of unneeded patterns, you can click File menu > Clean Up Document, and it removes all defs which are not being used in the drawing. So as long as you delete all objects which might be using the pattern, and you don't expect you'll ever need the pattern in the future, that's a way to get rid of it. Clean Up Document gets rid of all kinds of defs which are not being used. It also includes gradients and markers, and probably a lot more stuff.

1 - Select an object which has the pattern applied to it, with the Selection tool
2 - Switch to the Node tool this will reveal the pattern handles, which can be used to move, rotate or scale
3 - Now finding the handles can sometimes be tricky. They consist of a tiny X, a tiny square and a tiny circle. If the pattern was packed with Inkscape, usually the X handle will be precisely on the top-left corner of the page. You may need to enable the page border is it's not already visible.

If it was a custom made pattern, the handles could either be right on top of the object it was applied to; or literally anywhere on the canvas, even outside the screen area. So you might have to look around for them.

The X handle moves the pattern. So for example, if you want to make sure all the stripes fall inside the object, and so that there are no half-stripes on the edge, you can move the whole thing, without moving the object which it's filling. Or if the handles are some distance from the object where I want it to fill, I like to drag it over next to the object, so I can see the changes I'm making, as they happen. Just grab the X with your mouse and drag it.

The square handle scales the pattern. Hold the Ctrl key to keep the proportions correct. Or if your intent is to change the proportions, don't hold the Ctrl key.

The circle handle rotates the pattern. I think the Ctrl key allows you to rotate in 15 degree steps (and that can be changed in Inkscape Preferences, as far as I know). I'm pretty sure the rotation center is the X handle.