Hello, I'm new to inkscape and I like to draw thick black lines around my drawings. Unfortunately, my drawings consist of multiple grouped objects with different colors.

The method I've made up is duplicating the group, joining all objects together as one path, making it black and doing an outset on that black path, then moving it behind the original drawing.

Merging all objects to one path is time consuming, because these objects can only be joined two at the time. Is there a method to convert the entire group to a path in one step?

Thanks!

I do a similar trick with my webcomic from time to time. This is the best approach I've found:

1) Select your group (or collection of objects)
2) Ungroup them - all the constituent parts should still remain selected
3) Repeat step 2 until there are no more groups in the selection. If you're lucky the status bar will list "123 objects of type path, circle..." and you can easily spot if "group" is in the list. If you're unlucky it will say "...of 5 types..." - in which case try ungrouping a couple more times just in case one of the 5 types is a group.
4) You should now have a lot of objects, all selected. Use "Path=>Object to Path" to convert them all to paths (may not be necessary, depending on the types of objects you've got, but won't usually do any harm to try it either)
5) Now you've got a load of selected paths. Use "Path=>Union" (ctrl-+ for speed) to combine them into one path.
6) Go into node edit mode to tidy up - complex collections of objects can result in "islands" of nodes which you can delete. "Path=>Simplify" might also help, but can sometimes loose too much detail.
7) Do the outset - though I usually just make the stroke thicker - set the colour and style, and send it to the back.

This is pretty much what you're already doing, but the key point is that you can union more than one path at a time. Other boolean operations don't make sense with more than one path, but union is an exception.

Hi..
Thank You Very Much... this was Very Useful while trying to convert flowed text into a path that eventually formatted to a perspective..

Since writing that over two years ago, I've switched to a different technique when I just want an outline of a group which has no holes in it:

1) Draw a rough rectangle around the group.
2) Flood fill ( ) the gap between the rectangle and the group. This gives you a path, with the shape of the group cut out of it.
3) Path > Break apart.
4) Delete the rectangle and the outer path.

You're now left with a path which is a silhouette of the original group. From here you can give it a thick stroke and drop it to the back, outset the path, drop it back and skew it with reduced opacity for a shadow effect, and so on.

Thanks for this long-ago tip! Someday when Inkscape has some kind of macro facility, this should definitely be one...

@ronburk: Inkscape does have 'macro facility' - only it's called 'extension'. Would you like to write one for this?