Many people do not mind the multi-window interface and the reason there wasn't a single-window one isn't some stagnation in progress but probably either opposition by the past maintainers to the idea of switching to a single-window one or not caring about it at all. Those fifteen years are hardly a measure of how Gimp fares in comparison to other image editors.

Can someone please explain to me the advantage of NOT having a single window display in an application such as this? I'm being serious here by the way ...

I remember when I tried GIMP many years ago. I had many little windows scattered across my desktop, and as soon as I misclicked on my background I'd suddenly lose focus of the app and all the sub-windows (toolbar, layers, etc) would disappear.

I either had to run my mouse back to the image's window or alt-tab back to the app to regain focus.

I found this incredibly terrible as a UI approach, but found no resources explaining why this is a good thing.

Partly - the Unix philosophy. Since you can swap out your window manager on X11, you can have your windows managed in any of a wide number of ways. If an application tries to manage subwindows on its own, there is a very good chance that it will do so differently than your global window manager. Assuming that there is a reason you picked the global WM that you did, it's rather disconcerting to be forced to use an inferior WM to manage Gimp's windows.

Add to that the multi-desktop, multi-monitor aspects (although detachable docking panes can help a lot with that).

Desktop environments on Unix systems on which GIMP was primarily supposed to run have always had virtual desktops, and with virtual desktops you can easily distribute the little tool windows to one desktop and the image windows to other desktops (or physical monitors if you fancy), which would not be possible in the single-window mode.

GIMP's multi-window interface is excellent when you have multiple monitors. Couple that with a good window manager and it's a lot better (IMO) than a single window with tools and other dialogs inside.

A multimonitor setup is great but it hardly answers the OP's question. When this decision was made multimonitor setups were rare...

I have my window manager manage the windows. I can use all my usual keys and shortcuts to modify/move/alter the windows. Eg mousescrolling over a window's title bar to reduce it to just its titlebar if I do not need it (there is a shortcut too, I forgot it though). Being able to make windows always in front. Being able to have multiple images open and move/resize them with alt+(left|right) mousedrag.

I like having only my image on screen. With multi-window mode, you can press the tab key to make tools windows appear/disappear.

When you're used to change tools via keyboard shortcut (and thus, don't need tools window most of the time), it's a great benefit.

It's useful to be able to put your tools on one monitor, and maximize the image on the other.

Would be cool to have a single window of image, and a separate single window of tools.

You can already do that : you can choose to only display toolbox window, and then add tabs (like a layer tab) in the toolbox window.

Ah, best of both worlds. I'll have to try that.

you CAN do that, dock all the dialogs in one single window

- you can move away the docks and have more screen estate for image editing; - press TAB and the docks go away, you have even more screen estate; - is easier when you work with more than one image at a time, for example using the clone tool you take samples from one image and move them to another or just when use one image as reference while drawing another.

For an app meant for the creative types, GIMP sure is ugly.

I also thought we were over mystery meat navigation, but it seems to be going strong at GIMP. Not only does having icons for each tab make it look incredibly busy, but it also makes it harder to learn and wastes a ton of screen space. I can't see a single benefit other than it doesn't look like Photoshop.

I wonder how hard it would be to redo the entire interface from scratch. I would love to design it, but no way do I want to navigate their bureaucracy.

I doubt theres much bureacracy, there are not that many core developers - probably going onto the mailinglist and providing some patches might be a start.

the single-window interface is overrated, i tried it in one early development releases and returned back to multi-windows

I don't understand the appeal of the multi-windows. I use GIMP at home and I often have multiple images open and find the tool windows disappear on me. It's frustrating. What's overrated about the single window interface and what draws you to multi window mode?

I guess the question is whether or not you're using a powerful window manager or not. Most window managers in linux support easy always-on-top and layers, so the multi-window UI really shines.

Ah, this makes sense now :) I haven't tried with a window manager. I'm typically in Windows at home and not always on Linux so I'll have to experiment.

The fact that I can use the window manager of my choice to manage the windows.

I don't even get how people can claim that there is a big difference anyhow - If we were brutally honest here, Photoshop is really only multi-windowed, too - with the main window maximized in the background and carrying the main menu.

And it still has garbage like the pepper brush.