All platforms:
j2re build 48

In the JNLP runtime settings dialog: if the add button is pressed,
then it requires the pressing of escape twice.

STEPS TO REPRODUCE THE PROBLEM:
1. Open the Control Panel.
2. Go to Java/Java Application Runtime Settings/View
3. In JNLP Runtime Settings click on Add button
4. Now try to close it, using Esc.
You need to press it twice to close this window.