Customizing the lightbox based on checkbox value

Here, I want to customise the lightbox in such a way that when a radio button with value “w_contactor” is selected, the contractor listing select box should be shown. If radio button with value “wo_contactor” is selected , select box should be hidden and the text box should be shown.

Hello Mathew,
Gantt doesn’t have a built-in way to do that. You need to implement a custom solution by using the Gantt API and Javascript.
The easiest way to do that is to attach the onchange event and modify the styles of the section you want to hide or show.
Here is an example of how it can be implemented: