Hi Emmanuel,
You can follow the below mentioned approach for your requirment.
Implementation Steps:
1) Define custom style class to the popover widget, e.g. cust-popover

2) Define custom style class to the Apply Filter button, e.g. filter_btn

3) Define screen onReady handler and execute the below JS
document.querySelector('.cust-popover').addEventListener('click', function (e) {
if(!e.target.closest('.filter_btn') && e.target.closest('.popover-bottom')) {
e.stopPropagation();
}
});
Note: The above approach will prevent the popover being closed while clicking inside the popover section other than the Apply filter button.
See this demo screen: PopoverJS
Refer to the attached oml file.
I hope this helps you!
Kind regards,
Benjith Sam