Slight adjustment to warning that a shared folder does not exist

[Wand]

Sometimes a shared folder may be crucial to the operation of a VM. Currently upon a VM startup, if the folder does not exist, a message appears warning the user that a non-fatal error has occurred.

The suggestion here is for this dialog. Instead of it having just an OK button, it should have an additional message saying "Do you wish to proceed?" and the OK button should be a "Yes/No" buttons set. That way, the user would be able/responsible to decide if the error is indeed a non-fatal one or not. If OK is pressed, the normal startup of the VM should continue (as happens today). If Cancel is pressed, the VM should not startup.

An additional idea would be to add a new option ("Essential for startup") in the "shared folder add" dialog, under the "readonly" and "automount" options, which:

• if checked, the question mentioned above will not be asked but perform the same actions as if Cancel has been pressed
• if not checked, the question mentioned above will not be asked but perform the same actions as if OK has been pressed
• if grayed-out (should be the default state), the question should be asked so that the user decides if he wants the VM to start or not.

[Wand]

Also, the "add/edit share" dialog could be a little larger...