Okay I reinstalled Code::Blocks and SFML now completely. (Yeah all files including the ones in %appdata% etc)
I think the problem might have been that I chose the 64 bit version of SFML even tho I had the 32 bit compiler installed?
Anyway, this time I chose 32 bit with the 32 bit compiler. And now I get other errors (but they are still undefined reference-errors):
-------------- Clean: Debug in SFML_Test_TEST (compiler: GNU GCC Compiler (SFML 2.4.1))---------------
Cleaned "SFML_Test_TEST - Debug"
-------------- Build: Debug in SFML_Test_TEST (compiler: GNU GCC Compiler (SFML 2.4.1))---------------
mingw32-g++.exe -Wall -g -std=c++11 -DGLEW_STATIC -DSFML_STATIC -DUNICODE -IC:\SFML-2.4.1\include -c D:\C++\Projekte\SFML_Test_TEST\main.cpp -o obj\Debug\main.o
mingw32-g++.exe -LC:\SFML-2.4.1\lib -o bin\Debug\SFML_Test_TEST.exe obj\Debug\main.o C:\SFML-2.4.1\lib\libsfml-graphics-s.a C:\SFML-2.4.1\lib\libfreetype.a C:\SFML-2.4.1\lib\libjpeg.a C:\SFML-2.4.1\lib\libsfml-window-s.a C:\SFML-2.4.1\lib\libsfml-audio-s.a C:\SFML-2.4.1\lib\libopenal32.a C:\SFML-2.4.1\lib\libFLAC.a C:\SFML-2.4.1\lib\libvorbisenc.a C:\SFML-2.4.1\lib\libvorbisfile.a C:\SFML-2.4.1\lib\libvorbis.a C:\SFML-2.4.1\lib\libogg.a C:\SFML-2.4.1\lib\libsfml-network-s.a C:\SFML-2.4.1\lib\libsfml-system-s.a
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0x34f): undefined reference to `glClearColor@16'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0x9c8): undefined reference to `glMatrixMode@4'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0x9d0): undefined reference to `glPopMatrix@0'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0x9dc): undefined reference to `glMatrixMode@4'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0x9e4): undefined reference to `glPopMatrix@0'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0x9f0): undefined reference to `glMatrixMode@4'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0x9f8): undefined reference to `glPopMatrix@0'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0x9fd): undefined reference to `glPopClientAttrib@0'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0xb9e): undefined reference to `glViewport@16'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0xbad): undefined reference to `glMatrixMode@4'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0xbc6): undefined reference to `glLoadMatrixf@4'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0xbd5): undefined reference to `glMatrixMode@4'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0xe19): undefined reference to `glBlendFunc@8'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0xf5a): undefined reference to `glDisable@4'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0xf69): undefined reference to `glDisable@4'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0xf78): undefined reference to `glDisable@4'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0xf87): undefined reference to `glDisable@4'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0xf96): undefined reference to `glEnable@4'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0xfa5): undefined reference to `glEnable@4'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0xfb4): undefined reference to `glMatrixMode@4'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0xfc3): undefined reference to `glEnableClientState@4'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0xfd2): undefined reference to `glEnableClientState@4'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0xfe1): undefined reference to `glEnableClientState@4'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0x100e): undefined reference to `glLoadMatrixf@4'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0x10c1): undefined reference to `glPushClientAttrib@4'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0x10d0): undefined reference to `glPushAttrib@4'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0x10df): undefined reference to `glMatrixMode@4'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0x10e7): undefined reference to `glPushMatrix@0'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0x10f3): undefined reference to `glMatrixMode@4'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0x10fb): undefined reference to `glPushMatrix@0'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0x1107): undefined reference to `glMatrixMode@4'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0x110f): undefined reference to `glPushMatrix@0'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0x11dd): undefined reference to `glLoadMatrixf@4'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0x1200): undefined reference to `glLoadMatrixf@4'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0x12ca): undefined reference to `glVertexPointer@16'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0x12f4): undefined reference to `glColorPointer@16'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0x131e): undefined reference to `glTexCoordPointer@16'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0x1344): undefined reference to `glDrawArrays@12'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0x364): undefined reference to `glClear@4'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0xa05): undefined reference to `glPopAttrib@0'
C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj):RenderTarget.cpp:(.text+0x1443): undefined reference to `glLoadMatrixf@4'
C:/Program Files (x86)/CodeBlocks/MinGW/bin/../lib/gcc/mingw32/4.9.2/../../../../mingw32/bin/ld.exe: C:\SFML-2.4.1\lib\libsfml-graphics-s.a(RenderTarget.cpp.obj): bad reloc address 0x98 in section `.rdata'
C:/Program Files (x86)/CodeBlocks/MinGW/bin/../lib/gcc/mingw32/4.9.2/../../../../mingw32/bin/ld.exe: final link failed: Invalid operation
collect2.exe: error: ld returned 1 exit status
Process terminated with status 1 (0 minute(s), 1 second(s))
42 error(s), 0 warning(s) (0 minute(s), 1 second(s))
regards, TPRammus