Clear image sizes buffer to prevent graphical glitches

imagescrollareagl.cpp

@@ -126,7 +126,10 @@ void ImageWidget::allocateThumbnails(int count)
     m_thumbnailTexture->setLayers(count);
     m_thumbnailTexture->allocateStorage();
     m_bufferSizes->bind();
-    m_bufferSizes->allocate(count * sizeof(float)*3);
+    float *tmp = new float[count*3];
+    memset(tmp, 0, count * sizeof(float)*3);
+    m_bufferSizes->allocate(tmp, count * sizeof(float)*3);
+    delete [] tmp;
     m_thumbnailCount = count;
 }