Program: 30790
Project: 30790
Buggy source:
@Override public void initGui(){
  super.initGui();
  buttonList.add(plus1=new GuiButton(0,this.guiLeft + 20,this.guiTop + 32,22,20,"String_Node_Str"));
  buttonList.add(plus10=new GuiButton(0,this.guiLeft + 48,this.guiTop + 32,28,20,"String_Node_Str"));
  buttonList.add(plus100=new GuiButton(0,this.guiLeft + 82,this.guiTop + 32,32,20,"String_Node_Str"));
  buttonList.add(plus1000=new GuiButton(0,this.guiLeft + 120,this.guiTop + 32,38,20,"String_Node_Str"));
  buttonList.add(minus1=new GuiButton(0,this.guiLeft + 20,this.guiTop + 69,22,20,"String_Node_Str"));
  buttonList.add(minus10=new GuiButton(0,this.guiLeft + 48,this.guiTop + 69,28,20,"String_Node_Str"));
  buttonList.add(minus100=new GuiButton(0,this.guiLeft + 82,this.guiTop + 69,32,20,"String_Node_Str"));
  buttonList.add(minus1000=new GuiButton(0,this.guiLeft + 120,this.guiTop + 69,38,20,"String_Node_Str"));
  ItemStack myIcon=null;
  Object target=((AEBaseContainer)inventorySlots).getTarget();
  if (target instanceof PartStorageBus) {
    myIcon=AEApi.instance().parts().partStorageBus.stack(1);
    OriginalGui=GuiBridge.GUI_STORAGEBUS;
  }
  if (target instanceof TileDrive) {
    myIcon=AEApi.instance().blocks().blockDrive.stack(1);
    OriginalGui=GuiBridge.GUI_DRIVE;
  }
  if (target instanceof TileChest) {
    myIcon=AEApi.instance().blocks().blockChest.stack(1);
    OriginalGui=GuiBridge.GUI_CHEST;
  }
  if (OriginalGui != null)   buttonList.add(originalGuiBtn=new GuiTabButton(this.guiLeft + 154,this.guiTop,myIcon,myIcon.getDisplayName(),itemRender));
  priority=new GuiTextField(fontRendererObj,this.guiLeft + 62,this.guiTop + 57,59,fontRendererObj.FONT_HEIGHT);
  priority.setEnableBackgroundDrawing(false);
  priority.setMaxStringLength(16);
  priority.setTextColor(0xFFFFFF);
  priority.setVisible(true);
  priority.setFocused(true);
  ((ContainerPriority)inventorySlots).setTextField(priority);
}

Fixed version (ground truth):
@Override public void initGui(){
  super.initGui();
  buttonList.add(plus1=new GuiButton(0,this.guiLeft + 20,this.guiTop + 32,22,20,"String_Node_Str"));
  buttonList.add(plus10=new GuiButton(0,this.guiLeft + 48,this.guiTop + 32,28,20,"String_Node_Str"));
  buttonList.add(plus100=new GuiButton(0,this.guiLeft + 82,this.guiTop + 32,32,20,"String_Node_Str"));
  buttonList.add(plus1000=new GuiButton(0,this.guiLeft + 120,this.guiTop + 32,38,20,"String_Node_Str"));
  buttonList.add(minus1=new GuiButton(0,this.guiLeft + 20,this.guiTop + 69,22,20,"String_Node_Str"));
  buttonList.add(minus10=new GuiButton(0,this.guiLeft + 48,this.guiTop + 69,28,20,"String_Node_Str"));
  buttonList.add(minus100=new GuiButton(0,this.guiLeft + 82,this.guiTop + 69,32,20,"String_Node_Str"));
  buttonList.add(minus1000=new GuiButton(0,this.guiLeft + 120,this.guiTop + 69,38,20,"String_Node_Str"));
  ItemStack myIcon=null;
  Object target=((AEBaseContainer)inventorySlots).getTarget();
  if (target instanceof PartStorageBus) {
    myIcon=AEApi.instance().parts().partStorageBus.stack(1);
    OriginalGui=GuiBridge.GUI_STORAGEBUS;
  }
  if (target instanceof PartFormationPlane) {
    myIcon=AEApi.instance().parts().partFormationPlane.stack(1);
    OriginalGui=GuiBridge.GUI_FPLANE;
  }
  if (target instanceof TileDrive) {
    myIcon=AEApi.instance().blocks().blockDrive.stack(1);
    OriginalGui=GuiBridge.GUI_DRIVE;
  }
  if (target instanceof TileChest) {
    myIcon=AEApi.instance().blocks().blockChest.stack(1);
    OriginalGui=GuiBridge.GUI_CHEST;
  }
  if (OriginalGui != null)   buttonList.add(originalGuiBtn=new GuiTabButton(this.guiLeft + 154,this.guiTop,myIcon,myIcon.getDisplayName(),itemRender));
  priority=new GuiTextField(fontRendererObj,this.guiLeft + 62,this.guiTop + 57,59,fontRendererObj.FONT_HEIGHT);
  priority.setEnableBackgroundDrawing(false);
  priority.setMaxStringLength(16);
  priority.setTextColor(0xFFFFFF);
  priority.setVisible(true);
  priority.setFocused(true);
  ((ContainerPriority)inventorySlots).setTextField(priority);
}