I've find several places in several components, which I've check - I'll create separate issues for this. There is a chance what there are leak in other components, which I did not inspect.

The main reason of the issue is -> sometimes (after long work with related plugins) this leads to

Error
Unhandled event loop exception

org.eclipse.swt.SWTError: No more handles
	at org.eclipse.swt.SWT.error(SWT.java:4308)
	at org.eclipse.swt.SWT.error(SWT.java:4197)
	at org.eclipse.swt.SWT.error(SWT.java:4168)
	at org.eclipse.swt.widgets.Widget.error(Widget.java:468)
...

and only restart of whole eclipse can helps.