Description:
Visual glitches when I draw over previous brush stokes. It's got a black "torn edge" look that's probably due to a bug in the code concerning the update region or blending state. This problem wasn't in 2.5 but appeared in 2.5.1 after I upgraded. I use Krita a lot, and now the program's completely unusable, so this is kinda major for me.


Additional info:
I'm running Arch 64bit on an AMD Phenom II x4 920 / ATi Radeon HD 4870 with the proprietary Catalyst-hook drivers from the official radeon-HD234k repo. However, I don't think it has to do with my video drivers because enabling/disabling OpenGL canvas makes no difference.

I'm using a few Multilib packages for GCC and libc, as well as lib32-libpng, and others

Running Krita from a terminal gives these errors:


(WITH OPENGL CANVAS)

krita(23847)/koffice (lib pigment) KoColorConversionSystem::insertColorSpace: Cannot add node for "YCBCR (8-bit integer/channel)" , since there are no profiles available
krita(23847)/koffice (lib pigment) KoColorConversionSystem::insertColorSpace: Cannot add node for "YCBCR (16-bit integer/channel)" , since there are no profiles available
krita(23847)/koffice (lib pigment) KoColorConversionSystem::insertColorSpace: Cannot add node for "YCBCR (32-bit float/channel)" , since there are no profiles available
krita(23847)/kdecore (KLibrary) kde4Factory: The library "/usr/lib/kde4/kritahistorydocker.so" does not offer a qt_plugin_instance function.
krita(23847)/koffice (lib kopageapp) KoOdfLoadingContext::KoOdfLoadingContext: could not parse manifest document
krita(23847)/koffice (lib kopageapp) KoOdfLoadingContext::KoOdfLoadingContext: could not parse manifest document
X Error: BadWindow (invalid Window parameter) 3
Major opcode: 20 (X_GetProperty)
Resource id: 0x0
QActionGroup(0x8abc6f0)
QActionGroup(0x8abc6f0)
krita(23847)/koffice: Lcms2 error: 5 Read from memory error. Got 0 bytes, block should be of 128 bytes
krita(23847)/koffice: Lcms2 error: 5 Read from memory error. Got 0 bytes, block should be of 128 bytes
libpng warning: Duplicate iCCP chunk
libpng warning: Duplicate iCCP chunk
libpng warning: Duplicate iCCP chunk
libpng warning: Duplicate iCCP chunk
QGLShader::link: "Vertex shader(s) linked, fragment shader(s) linked.
"
QGLShader::link: "Vertex shader(s) linked, fragment shader(s) linked.



(WITHOUT OPENGL CANVAS)

krita(23895)/koffice (lib pigment) KoColorConversionSystem::insertColorSpace: Cannot add node for "YCBCR (8-bit integer/channel)" , since there are no profiles available
krita(23895)/koffice (lib pigment) KoColorConversionSystem::insertColorSpace: Cannot add node for "YCBCR (16-bit integer/channel)" , since there are no profiles available
krita(23895)/koffice (lib pigment) KoColorConversionSystem::insertColorSpace: Cannot add node for "YCBCR (32-bit float/channel)" , since there are no profiles available
krita(23895)/kdecore (KLibrary) kde4Factory: The library "/usr/lib/kde4/kritahistorydocker.so" does not offer a qt_plugin_instance function.
krita(23895)/koffice (lib kopageapp) KoOdfLoadingContext::KoOdfLoadingContext: could not parse manifest document
krita(23895)/koffice (lib kopageapp) KoOdfLoadingContext::KoOdfLoadingContext: could not parse manifest document
X Error: BadWindow (invalid Window parameter) 3
Major opcode: 20 (X_GetProperty)
Resource id: 0x1
krita(23895)/koffice: Lcms2 error: 5 Read from memory error. Got 0 bytes, block should be of 128 bytes
krita(23895)/koffice: Lcms2 error: 5 Read from memory error. Got 0 bytes, block should be of 128 bytes
QActionGroup(0x8a5a8f0)
QActionGroup(0x8a5a8f0)
krita(23895)/koffice: Lcms2 error: 5 Read from memory error. Got 0 bytes, block should be of 128 bytes
krita(23895)/koffice: Lcms2 error: 5 Read from memory error. Got 0 bytes, block should be of 128 bytes
libpng warning: Duplicate iCCP chunk
libpng warning: Duplicate iCCP chunk
libpng warning: Duplicate iCCP chunk
libpng warning: Duplicate iCCP chunk




Steps to reproduce:
1. Open Krita, make new file
2. Paint a stroke with default brush, release mouse/pen
3. Paint a stroke over the previous one

Hint: it's hard to see if using a mouse with the default brush. Choose a larger, softer brush to see the glitch.