Created attachment 1207636 [details]
UI log

Description of problem:
When creating a disk for a new VM, TypeError exception is thrown in the UI.

Version-Release number of selected component (if applicable):
oVirt Engine Version: 4.1.0-0.0.master.20161004211324.git0cd2c3e.el7.centos

How reproducible:
Always on this setup.

Steps to Reproduce:
1. Open new VM window and input name for the VM (test_vm for example).
2. Create new virtual disk, 20GB size, leave all other fields untouched.
3. Press OK in the new virtual disk window.

Actual results:
Exception is thrown in the UI.

Expected results:
VM should be created with a new disk attached to it.

Additional info:
ui.log:
Caused by: com.google.gwt.core.client.JavaScriptException: (TypeError) 
 __gwt$exception: <skipped>: a is null
	at org.ovirt.engine.ui.common.widget.AddRemoveRowWidget$AddRemoveRowPanel.$setButtonsEnabled(AddRemoveRowWidget.java:377)
	at org.ovirt.engine.ui.common.widget.AddRemoveRowWidget.$setButtonsEnabled(AddRemoveRowWidget.java:344)
	at org.ovirt.engine.ui.common.widget.AddRemoveRowWidget.toggleGhost(AddRemoveRowWidget.java:497)
	at org.ovirt.engine.ui.common.widget.AddRemoveRowWidget$3.onValueChange(AddRemoveRowWidget.java:232)
	at com.google.gwt.event.logical.shared.ValueChangeEvent.dispatch(ValueChangeEvent.java:127) [gwt-servlet.jar:]
	at com.google.gwt.event.shared.GwtEvent.dispatch(GwtEvent.java:76) [gwt-servlet.jar:]
	at com.google.web.bindery.event.shared.SimpleEventBus.$doFire(SimpleEventBus.java:173) [gwt-servlet.jar:]
	... 37 more

Engine.log:
2016-10-05 18:41:44,901 INFO  [org.ovirt.engine.docs.utils.servlet.ContextSensitiveHelpMappingServlet] (default task-17) [] Context-sensitive help is not installed. Manual directory doesn't exist: /usr/share/ovirt-engine/manual