Yes. Notepad++ has a latest release 5.5.1 has some built in themes you can take advantage of. If you want little bit more customization, you can change the colors of every element in UI as you want.
Step 1. Assuming you already have
Notepad++ installed, navigate your
browser over to the Textmate Theme
Directory.
Step 2. Choose a rad looking theme and
download it.
Step 3. Fire up Notepad++ and open the
.tmTheme file you just downloaded.
Step 4. Select all (Ctrl+A) and copy
(Ctrl+C)
Step 5. Now navigate your browser over
to the theme converter page.
Step 6. Paste what you copied from
Notepad++ into the big textbox and
click the download button and save the
file.
Step 7. In Explorer, navigate to:
C:\Documents and
Settings\%%USERNAME%%\Application
Data\Notepad++\
Step 8. Locate the original styler
theme file (stylers.xml) and rename it
to something like original.stylers.xml
Step 9. Take the file you downloaded
from Step 6 and move it to the
location in Step 7.
Step 10. Rename the file you just
moved to stylers.xml
Step 11. Close Notepad++ and reopen
it.
Step 12. Enjoy your new colors!
Hope this helps.
Best Answer
Use Notepad++ plugin TopMost and select the option 'Make my window transparent'.
My experience with this plugin has been very limited and I came to know about it when I had the exact opposite problem with my Notepad++: my Notepad++ window became unexpectedly transparent. I was able to remove the transparency by unflagging the 'Make my window transparent' option from the Plugin->TopMost menu in NotePad++.
This is the Plugin description that Notepad++ provides: