private DataTypeSelectionDialog showSelectionDialog(ListingActionContext context,
			int maxStorageSize, PluginTool tool, DataTypeManager dataTypeManager) {
		DataTypeSelectionDialog selectionDialog = new DataTypeSelectionDialog(tool, dataTypeManager,
			maxStorageSize, AllowedDataTypes.FIXED_LENGTH);
		DataType currentDataType = plugin.getCurrentDataType(context);
		selectionDialog.setInitialDataType(currentDataType);
		tool.showDialog(selectionDialog);
		return selectionDialog;
	}
Returns the storage size of the variable at the current cursor location in the
given listing/program.

@return -1 if the selected item in the listing is not a variable type
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/function/ChooseDataTypeAction.java