[gnome-boxes] tests: Look for 'Back' in correct window

[Zeeshan Ali Khattak <zeeshanak src gnome org>]

commit 6423572970fcbea8308a13cf567df06a7d617c63
Author: Zeeshan Ali (Khattak) <zeeshanak gnome org>
Date:   Mon Feb 2 10:13:42 2015 +0000

    tests: Look for 'Back' in correct window
    
    Since customization view (along with wizard, that it's part of) is now
    in a separate window. Update step implementation to look for 'Back' in
    correct place.

 tests/steps/general.py |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/tests/steps/general.py b/tests/steps/general.py
index 72fd50a..8c6d4b9 100644
--- a/tests/steps/general.py
+++ b/tests/steps/general.py
@@ -41,7 +41,7 @@ def customize_vm(context):
     pressKey('Page_Up')
     pressKey('Page_Up')
 
-    context.app.children[0].children[0].children[3].child('Back').click()
+    context.app.findChildren(lambda x: x.name == 'Back' and x.showing)[0].click()
     sleep(0.5)
 
 @step('Go into "{vm}" box')