Tested on Build 1.9.79

In the Mail Merge Wizard, the transition between Step 6 and Step 7 displays a 
progress dialog which is non-modal. Clicking other buttons in the Wizard while 
this progress dialog is displayed results in a program Crash.

Setup steps:
1.Start a new Writer document.
2.Start the Mail Merge Wizard (Tools >> Mail Merge Wizard).
3.Click Next to go to Step 2.
4.Select Letter and Click Next to go to Step 3.
5.Select an Address List with at least 13 entries (I selected the Bibliography 
Database).
6.Click Next till you reach Step 6.

Steps for Crash 1:
1.Perform the Setup steps.
2.Click Next to bring up the progress dialog.
3.When the progress dialog is displayed and the progress counter increases, 
click the Next button on the main Wizard dialog.
4.Notice how the progress countdown restarts.
5.Now click the “Cancel†button in the progress dialog box.
6.This results in a program crash.

Steps for Crash 2:
1.Perform the Setup steps.
2.Click Next to bring up the progress dialog.
3.When the progress dialog is displayed and the progress counter increases, 
click the Next button on the main Wizard dialog.
4.Now click the “Back†button on the main Wizard dialog box.
5.The Wizard dialog box goes away, though the progress dialog is still 
displayed.
6.After the progress dialog countdown is complete, the program crashes.

Expected behaviour: The progress dialog box should be modal and not allow the 
user to click on the other buttons in the main wizard dialog.

Observed behaviour: The progress dialog box is non-modal and allows the user 
to click other buttons in the main wizard dialog, causing a program crash to 
occur.