Next button remains enabled when no items are selected after toggling "Hide items that are already installed"

[subyssurendran666]

Steps to replicate

• Open Help → Install New Software…
• Select an update site that contains installable plugins.
• Click Select All or manually select any plugin from the list.
• Enable the checkbox "Hide items that are already installed".
• Observe the plugin list and selection state and the Next button.

Expected Behavior
If no plugins are visibly selected (all checkboxes unchecked), the Next button should be disabled.

[subyssurendran666]

I will work on this issue

[subyssurendran666]

The issue is exists in the other checkboxes. So those will accommodate along with this ticket.