The Basic_Mix_Over smudge brush creates these artifacts when using a graphics tablet (Wacom bamboo P&T on WinXP).
http://postimg.org/image/yac6mlucj/
When blending 2 colours, the first few dabs creates the artifacts in the image. (The image i used has a flat colour in which case I'd expect no visible blending cos blending grey with grey equals grey, but instead the colour from the layer below appears in the artifacts). With the mouse, i do get the expected result, that is flat colour produces the same flat colour and blending 2 colours blends without the artifacts.

Just wondering if this is a bug or something that can be changed in the settings (I was using default settings in the example)

looks like it is a bug. Just checked on Ubuntu 12.04 and it works perfectly.

Yes, definitely a bug.

Should it go in the bug tracker? Also just installed krita_2.7.8.7 on XP32 and I get an error when trying to start it -

krita.exe - Entry Point Not Found
The procedure entry point inet_pton could not be located in the dynamic link library WS2_32.dll.

I uninstalled previous version before installing this one. (I also deleted the previous installer and it doesn't exist on kogmbh - without the Calligra Suit; so I can't use Krita anymore!)

Yes, recently some dependency I added broke Krita on XP. You can still download old versions, though -- I didn't delete those from the server.

These are the available packages, just subsitute those for the one in the download link:

krita_2.4.7.5.msi
krita_2.4.7.6.msi
krita_2.5.0.0_msvc_14_08_2021.msi
krita_2.5.2.0_msvc_13_09_2012.msi
krita_2.5.7.0.msi
krita_2.5.7.1.msi
krita_2.5.7.2.msi
krita_2.5.9.0.msi
krita_2.6.0.0.msi
krita_2.6.2.0.msi
krita_2.6.8.3.msi
krita_2.6.8.4.msi
krita_2.6.8.5.msi
krita_2.6.8.8.msi
krita_2.6_mingw64_14_08_2012.msi
krita_2.7.8.0.msi
krita_2.7.8.10_64.msi
krita_2.7.8.2.msi
krita_2.7.8.7.msi
krita_2.7.8.9_64.msi
kritasketch_0.9.21.0.msi
kritasketch_0.9.30.0.msi
kritasketch_0.9.31.0.msi
kritasketch_1.0.0.1.msi
krita_unstable.msi

Thanks. Is i possible to know the last version before the dependency was added? Otherwise I'd have to install a few versions until I get it right (I was using krita_2.6.8.8 previously)

I think, but might be mistaken, that krita_2.7.8.2.msi was the last one that worked on XP.

Thanks once again.