This was discovered while trying to debug some Installation Tests. We start Eclipse that way: https://github.com/jbosstools/jbosstools-install-grinder/blob/master/scripts/src/main/groovy/testInstall.groovy#L96 (java -jar ... -product ... -application org.eclipse.swtbot.swtbottestapplication -testProduct ... -testApplication ...).
When running SWTBot to perform tests that install all Software from Central, when those are failing due to bad p2 plan; then there is no pop-up to warn about failing plan.
When starting Eclipse normally, we can see a pop-up telling which "Problems occured".