QGraphicsView OpenGL view port error

I have problem running a QGraphicsView in a QGLWidget view port.
Trying to solve the problem, I made a test modifying the Animated Tiles demo adding a OpenGL view port and a QGraphicsDropShadowEffect to tile items. Attached you'll find the modified example main.cpp. The error description follow:

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'animatedtiles.exe': Loaded 'C:\Windows\SysWOW64\crypt32.dll'
'animatedtiles.exe': Loaded 'C:\Windows\SysWOW64\msasn1.dll'
QGLShader::link: "Fragment shader(s) linked, vertex shader(s) linked.
"
QGLShader::link: "Fragment shader(s) linked, vertex shader(s) linked.
"
QGLShader::link: "Fragment shader(s) linked, vertex shader(s) linked.
"
First-chance exception at 0x69863ba9 in animatedtiles.exe: 0xC0000005: Access violation reading location 0xabababbf.
First-chance exception at 0x69863ba9 in animatedtiles.exe: 0xC0000005: Access violation reading location 0xabababbf.
QGLShader::link: "Fragment shader(s) failed to link, vertex shader(s) failed to link.
unexpected error.
unexpected error.
"
"Shader program failed to link,
Shaders Used:
Vertex shader: main=MainWithTexCoordsVertexShader, position=PositionOnlyVertexShader:
#define lowp
#define mediump
#define highp

attribute highp vec2 textureCoordArray;
varying highp vec2 textureCoords;
void setPosition();
void main(void)

attribute highp vec2 vertexCoordsArray;
attribute highp vec3 pmvMatrix1;
attribute highp vec3 pmvMatrix2;
attribute highp vec3 pmvMatrix3;
void setPosition(void)

Fragment shader: main=MainFragmentShader, srcPixel=CustomImageSrcFragmentShader, composition=NoCompositionModeFragmentShader, mask=NoMaskFragmentShader:
#define lowp
#define mediump
#define highp

lowp vec4 srcPixel();
void main()

varying highp vec2 textureCoords;
uniform lowp sampler2D imageTexture;
lowp vec4 customShader(lowp sampler2D texture, highp vec2 coords);
lowp vec4 srcPixel()

uniform lowp vec4 shadowColor;lowp vec4 customShader(lowp sampler2D src, highp vec2 srcCoords)

Error Log:
Fragment shader(s) failed to link, vertex shader(s) failed to link.
unexpected error.
unexpected error.
"
First-chance exception at 0x630741b4 (QtOpenGLd4.dll) in animatedtiles.exe: 0xC0000005: Access violation reading location 0x00000024.
Unhandled exception at 0x630741b4 (QtOpenGLd4.dll) in animatedtiles.exe: 0xC0000005: Access violation reading location 0x00000024.