Program: 34600
Project: 34600
Buggy source:
private void renderScreen(int mouseX,int mouseY,float partialTickTime){
  GL11.glEnable(GL12.GL_RESCALE_NORMAL);
  GL11.glColor4f(1F,1F,1F,1F);
  GL11.glEnable(GL11.GL_BLEND);
  GL11.glBlendFunc(GL11.GL_SRC_ALPHA,GL11.GL_ONE_MINUS_SRC_ALPHA);
  renderBackgroundGUI();
  float offY=ptt(offsetY.value(),prevOffsetY,partialTickTime);
  int yLowerBound=-(int)offY - 32, yUpperBound=-(int)offY + height;
  GL11.glPushMatrix();
  GL11.glTranslatef(0F,offY,0F);
  for (  CategoryDisplayElement element : categoryElements)   element.render(this,yLowerBound,yUpperBound);
  for (  ObjectDisplayElement element : objectElements)   element.render(this,compendiumFile,yLowerBound,yUpperBound);
  RenderHelper.disableStandardItemLighting();
  GL11.glPopMatrix();
  if (!(mouseX < 24 || mouseX > width - 24 || mouseY < 24 || mouseY > height - 24)) {
    for (    CategoryDisplayElement element : categoryElements) {
      if (element.isMouseOver(mouseX,mouseY,(int)offY)) {
        GuiItemRenderHelper.setupTooltip(mouseX,mouseY,element.category.getTranslatedTooltip());
      }
    }
    for (    ObjectDisplayElement element : objectElements) {
      if (element.isMouseOver(mouseX,mouseY,(int)offY)) {
        GuiItemRenderHelper.setupTooltip(mouseX,mouseY,element.object.getTranslatedTooltip());
      }
    }
  }
  GL11.glEnable(GL11.GL_BLEND);
  GL11.glBlendFunc(GL11.GL_SRC_ALPHA,GL11.GL_ONE_MINUS_SRC_ALPHA);
  renderFragmentCount(width - 90,24);
  for (int a=0; a < 2; a++)   pageArrows[a].visible=false;
  GL11.glEnable(GL11.GL_BLEND);
  GL11.glBlendFunc(GL11.GL_SRC_ALPHA,GL11.GL_ONE_MINUS_SRC_ALPHA);
  if (currentObject != null)   renderPaper(width / 2,height / 2,mouseX,mouseY);
  prevMouseX=mouseX;
}

Fixed version (ground truth):
private void renderScreen(int mouseX,int mouseY,float partialTickTime){
  GL11.glEnable(GL12.GL_RESCALE_NORMAL);
  GL11.glColor4f(1F,1F,1F,1F);
  GL11.glEnable(GL11.GL_BLEND);
  GL11.glBlendFunc(GL11.GL_SRC_ALPHA,GL11.GL_ONE_MINUS_SRC_ALPHA);
  renderBackgroundGUI();
  float offY=ptt(offsetY.value(),prevOffsetY,partialTickTime);
  int yLowerBound=-(int)offY - 32, yUpperBound=-(int)offY + height;
  GL11.glPushMatrix();
  GL11.glTranslatef(0F,offY,0F);
  for (  CategoryDisplayElement element : categoryElements)   element.render(this,yLowerBound,yUpperBound);
  for (  ObjectDisplayElement element : objectElements) {
    if (!element.object.isHidden()) {
      element.render(this,compendiumFile,yLowerBound,yUpperBound);
      element.object.connectToChildren(width / 2,48,ObjectDisplayElement.lineRenderer);
    }
  }
  RenderHelper.disableStandardItemLighting();
  GL11.glPopMatrix();
  if (!(mouseX < 24 || mouseX > width - 24 || mouseY < 24 || mouseY > height - 24)) {
    for (    CategoryDisplayElement element : categoryElements) {
      if (element.isMouseOver(mouseX,mouseY,(int)offY)) {
        GuiItemRenderHelper.setupTooltip(mouseX,mouseY,element.category.getTranslatedTooltip());
      }
    }
    for (    ObjectDisplayElement element : objectElements) {
      if (element.isMouseOver(mouseX,mouseY,width / 2,(int)offY)) {
        GuiItemRenderHelper.setupTooltip(mouseX,mouseY,element.object.getTranslatedTooltip());
      }
    }
  }
  GL11.glEnable(GL11.GL_BLEND);
  GL11.glBlendFunc(GL11.GL_SRC_ALPHA,GL11.GL_ONE_MINUS_SRC_ALPHA);
  renderFragmentCount(width - 90,24);
  for (int a=0; a < 2; a++)   pageArrows[a].visible=false;
  GL11.glEnable(GL11.GL_BLEND);
  GL11.glBlendFunc(GL11.GL_SRC_ALPHA,GL11.GL_ONE_MINUS_SRC_ALPHA);
  if (currentObject != null)   renderPaper(width / 2,height / 2,mouseX,mouseY);
  prevMouseX=mouseX;
}