If you add new dialog items or static variables to your custom block, they will need to be initialized. The easiest way to do this is in the openModel message handler. This is called whenever a model is loaded. If you delete or change the dimensions of dialog items or static variables, the data in the existing blocks may not match up correctly with the data in the existing blocks. To avoid this, delete the existing blocks and re-add them to the model. You can also use the "hide" feature to hide the dialog item. You should do this if your blocks are being used in models where it would be inconvenient to replace each instance of the block.