Okay, I posted a download link to an alternate gtkrc file that disables the background gradient. Please try it and let me know what you think. - Mar 17 2010
Looking at your screenshot a second time, I can see a few things that you can do to improve the visual appearance.

1 - Enable the separator between title bar and window contents. It helps to mask the disparity a bit. You can do this by going into System Settings -> Appearance -> Windows -> select the "Fine Tuning" tab and check the box for "Draw separator...".
2 - While you are in the window decoration properties, you may want to change your window glow color to fit the theme better. You can do this under the "Shadows" tab. I have my window glow set as such:
- Inner Color: #B2DAFF
- Outer Color: #346186
3 - In your GTK file pickers, right-click in the file selection area and de-select "Show size column". This will lighten the colors in the file selector.

If anybody knows why the colors change with the file size shown, I'm all ears... I couldn't find anything in the theme's gtkrc file that is responsible for this behavior. - Mar 16 2010
It is not possible using the pixbuf engine to get the window decoration to match the color of the contents in all cases. The following GTK windows won't fully match the gradient:
- Any window without a menu bar (such as the file picker in your screenshot)
- Smaller windows
- Some GTK apps will have spots of solid background color rather than the gradient, and other anomalies (example: scrollbar steppers in Firefox). Unfortunately, the more exaggerated gradient effect used in KDE 4.4 causes these artifacts to be more obvious than in previous versions. I have yet to find a way around this. It might not be possible with the pixbuf engine. - Mar 16 2010
Thanks for catching that! It is fixed now. - Mar 16 2010
Hey everyone! I have released a KDE 4.4 version of Oxygen-Molecule. I hope you like it :)

FYI, here are some other misc. settings that I use with this theme.

Oxygen window decoration active window glow:
- Inner Color: #B2DAFF
- Outer Color: #346186

Kwin desktop effects shadow plugin (used for menu shadows):
- X offset: 0
- Y offset: 2
- Opacity: 40%
- Fuzziness: 12
- Size: 8
- Color: #1F2A34
- Active windows have stronger shadows: yes
- Mar 16 2010
Just so everybody knows, I am working on the KDE 4.4 version of Oxygen-Molecule. I've been a bit strapped for time, though, which is why I haven't completed it yet. I will be using the "Oxygen-Cold" color scheme to avoid having to redo all the pixmaps. So far, I'm excited, because I've been able to get the background gradients to match almost perfectly! Even better than with the KDE 4.3 version! - Mar 09 2010
I'm trying out KDE SC 4.4 RC1 right now and liking it. However, the Oxygen theme has changed quite a bit in this release. I likely won't have the time anytime soon to make Oxygen-Molecule look like the new Oxygen theme, so in the meantime, simply use the Nitrogen theme instead, which is basically the old Oxygen.

One thing you'll want to do with the window decoration (whether you use the Oxygen or the Nitrogen window decoration): go to the "Window-Specific" tab in the system settings (Appearance -> Windows) and uncheck the box for "Window Class Name (Firefox)(Thunderbird)(Gimp)". - Jan 12 2010
Just writing to let you know that as of Oxygen-Molecule version 2.2, checkboxes in Gmail (and other websites) have been made smaller, and now look much better. - Jan 06 2010
Thanks for letting me know. This has been fixed in version 2.2. - Jan 06 2010
Yes, the GTK theme currently only works with one color setup. Craig Drummond has been working on a recolorable pixbuf engine, but it doesn't work quite well enough yet for what I need it to do. - Jan 06 2010
There is a patched version of pixbuf that fixes this. Here is the link: http://www.gnome-look.org/content/show.php/gtk2-engine-pixbuf+%28Patched%29?content=77783 - Nov 19 2009
Thanks! I will definitely consider that when I get some more time in a month or two. - Nov 19 2009
The separators in that screenshot don't look right. As for the colors, try importing the color scheme included with the Oxygen-Molecule theme, and see if that matches the window frame to the contents better. - Nov 19 2009
Making the checkboxes smaller will make them inconsistent with the KDE checkboxes. But, if you want to do that, I can send you the GIMP files I used for creating those pixmaps. That will make it easier to change the size. - Nov 04 2009
KDE's implementation of the background gradient stretches to fit the window size, but the pixbuf engine (which I use for Oxygen-Molecule) can only draw a background image that tiles. As a result, it is not possible to get the gradient to perfectly match the frame for all window sizes. I believe I've got it as close as I can to cover the average window size. - Nov 03 2009
Yeah, that bothers me too. I don't know how to fix it, though :( - Nov 03 2009
Okay, so I tried compiling QtCurve GTK version 0.69.0, which worked fine under Jaunty, and I still get the segfault. I'm not doing anything different, AFAIK, but something is different between Jaunty and Karmic to cause the segfault.

I couldn't figure out how to use gdb, unfortunately. I'll e-mail you some files that might be helpful. Obviously something is different between Karmic's packaged QtCurve and my custom compiled version, but what? - Nov 03 2009
I compiled and installed QtCurve 0.69.2 (KDE4, KDE3 & GTK) in Kubuntu Karmic, but when I set GTK apps to use QtCurve, GTK apps segfault immediately on launch. After uninstalling my compiled version and returning to the distro's packaged version (0.69.1), GTK apps work fine again. - Nov 02 2009
hydroxygen_iconset

Full Icon Themes by deviantdark 508 comments

By the way, this step is *not* necessary for Karmic. - Oct 09 2009
hydroxygen_iconset

Full Icon Themes by deviantdark 508 comments

Here's how I fixed the notification icons:

In your hydroxygen icons folder, create a folder called "scalable" and within that, one called "status". Then, copy all of the icons beginning with "notification-" from /usr/share/icons/Human/scalable/status into your newly created folder. - Oct 01 2009
Elegance

Plasma Themes by AdrienV 67 comments

Hey, I fixed it myself by removing the power logo from the dialog. My fix also corrects the problem where buttons were unreadable under KDE 4.3. Anyway, you can download my fix here:

http://www.mediafire.com/?mzemmyzdhyt - Sep 28 2009
Elegance

Plasma Themes by AdrienV 67 comments

Okay, so I fixed the problem myself by copying the button pixmap from the BlackGlass theme (http://www.kde-look.org/content/show.php?content=110034). I also fixed the shutdown dialog for KDE 4.3. You can download my fix here:

http://www.mediafire.com/?mzemmyzdhyt - Sep 28 2009
Elegance

Plasma Themes by AdrienV 67 comments

I should have mentioned that I'm using KDE 4.3.1. - Sep 28 2009
Elegance

Plasma Themes by AdrienV 67 comments

I really like the elegant theme on my system without compositing. The only problem is the "more" button on plasma notifications is light grey and the text that goes on it is also light grey, so it is unreadable. - Sep 27 2009
Yeah, it's impossible for me to match the shading in every instance, because the Oxygen theme doesn't just scale the titlebar lighting effect when you change a window's size. So, the shading will match more or less depending on the width of your window. Also, the vertical shading is off for smaller windows. There's simply no way to make everything match perfectly, due to limitations in the pixbuf engine. I tried to go for settings that would work in the greatest number of cases.

QtCurve is definitely a lot more flexible when it comes to colors, but there is no way to make it emulate the Oxygen theme. - Sep 08 2009
Yes, using Ozone or Oxygen window decorations with the default colors (or the colors included with the theme) should give you similar results to my screenshots. - Sep 08 2009
Unfortunately, the pixbuf engine doesn't support rounded corners. I even made pixmaps for it, but alas, they don't work (the corners appear black instead of transparent). - Sep 07 2009
I guess I'm not sure what you mean. What are window tabs vs. normal tabs (as in Firefox)? - Sep 07 2009
Hmmm... that would be beyond my knowledge. Perhaps somebody else might know the answer to that. - Sep 07 2009
To use a different icon set, set everything up per the instructions, then edit the /usr/share/themes/kde43-oxygen-molecule/gtk-2.0/gtkrc file and comment out line 8, which says 'include "icons.rc"'. Then change the icon theme name in line 12, which says 'gtk-icon-theme-name="oxygen"'

If you don't already know, you comment out a line by putting a '#' at the beginning of it. - Sep 06 2009
Oh, forgot to mention: As of version 2.0, Oxygen-Molecule no longer uses the Oxygen-Refit icon theme, but instead links directly to the Oxygen icon theme. If you are upgrading from an earlier version of Oxygen-Molecule, follow the directions closely, because some things are different. - Sep 06 2009
I hope you all enjoy the new release, for use with KDE 4.3. I wanted to make it recolorable, but I was having problems with the recolorable pixbuf engine, so that will have to wait for now. - Sep 06 2009
Working on the KDE 4.3 version; progress is slow right now. If all goes well, it will be automatically recolorable to match your KDE color settings :) - Sep 04 2009
Yes, I will be updating it for KDE 4.3 The main change in the theme is the way tabs are drawn. I'm currently playing with a version of the pixbuf engine that allows the theme to be recolored, so it might be a bit yet before the next version is released, but if all goes well, it should be well worth the wait :) - Aug 04 2009
deKorator

Various KDE 1.-4. Styles by skulptor 133 comments

I'm using KDE 4.3 RC3 with the latest deKorator (0.4.0.3), and whenever I maximize or restore a window, the icons/buttons on the left side of the title bar turn into black squares. When I move my mouse over the black squares, the icons reappear. This happens with every theme I've tried.

I'm not using desktop effects. If I enable desktop effects, instead of black squares, the icons are replaced with what looks like another area of the screen. Let me know if you need more info. - Jul 27 2009
Hi folks!

I just wanted to thank all of you who have contributed ideas and code changes to Oxygen-Molecule. I am in the process of preparing a house to sell, amid other things, so I likely won't be able to make any changes to the theme until at least mid-July. I do intend to incorporate the changes I've been sent, and also create a version for KDE 4.3 users. - Jun 20 2009
/gtk-2.0/others/menubar.png

You will probably also want to edit:
/gtk-2.0/others/toolbar.png - Jun 15 2009
Unfortunately, many of the colors are determined by the pixmaps. You will need to edit the pixmaps themselves to accomplish this. You can do it in GIMP. - Jun 14 2009
Wow! Thanks, CraigD! You obviously know a lot more about creating themes than I do. When I get some time, I'll update Oxygen-Molecule with your changes. - Jun 14 2009
This is currently a limitation of the pixbuf engine that is used to make this theme. It doesn't support transparency. I tried making the menu corners round, but where the corner clipped off, it just showed as black, so I had to make it square again. - Jun 14 2009
Is your oxygen icon theme located at /usr/share/icons/oxygen? The Oxygen-Molecule icon theme uses symbolic links to the original oxygen icons to save disk space. If Fedora stores the oxygen icons at a different location, then you can create a symbolic link as noted in my instructions. - Jun 14 2009
Currently, you can't tell when some widgets have focus (such as when navigating a dialog box with the TAB key).

To fix this, edit Oxygen-Molecule's gtkrc file. Go to line 21 and change it to:

GtkWidget:: focus-line-width = 1

instead of 0.

This will give you a dotted line around the object that has focus. This isn't 100% consistent with the KDE4 theme, but makes it a lot easier when navigating widgets with the keyboard.

Does anyone agree or disagree that this should be the default behavior? - Jun 07 2009
Once KDE 4.3 is out of beta, I'll look into making the matching GTK theme. - Jun 07 2009
Okay, the Firefox transparent buttons have been fixed in version 1.2 :) - May 23 2009
A number of the pixmaps are transparent, which is why the background color under buttons shows through. I actually kind-of like the way that buttons inherit their background color in Firefox, but I see that not everybody is fond of that behavior, so I will look into changing that in the next version. - May 21 2009
Okay, download is back up! I had to go with a file hosting service, so I am trying mediafire. Hopefully it will hold up with the bandwidth from you guys :)

If any of you have a better suggestion than mediafire, I'm all ears. - May 13 2009
Unfortunately, it does not. CraigD posted on the first comments page regarding a version of pixbuf that supports recoloring of pixmaps. I don't know how well that would work, especially considering some of my pixmaps have parts that would need to be recolored separately. Regardless, when I get some time, I might have a look at it. - May 13 2009
Sorry about that--I exceeded my bandwidth with my current web hosting with that file. I hope to have it uploaded to a new site by tomorrow (5/12/09). As a bonus, it will also be an improved version, 1.1 :) - May 12 2009
You should be able to install it in OpenSUSE, but I haven't tried it myself. Instructions are included in the download. Let me know if you're able to get it working on OpenSUSE, and how you did it, and I'll update the documentation if necessary. - May 07 2009
kde4.2-oxygen (modified)

GTK2 Themes by DeeZiD 28 comments

Unfortunately, in order to change most of the colors in the GTK+ theme, you will have to edit a ton of pixmaps, including gradients, etc. That's what I had to do to the original theme to make it match the default KDE colors. If anybody is up for the challenge, though, we could have some nice derivatives. - Apr 30 2009