[horde] Resume multiple draft emails will loss email

[Nethub Online - Ming]

Hi All,

We already submitted a bug here:https://bugs.horde.org/ticket/14828

Horde Groupware Webmail Edition: 5.2.22
Horde: 5.2.17
IMP: 6.2.21

How to duplicate the problem:
1. Save 3 emails (e.g. Email A, B, C) in draft folder
2. Go to drafts folder and select 2 draft emails (e.g. Email A, B)
3. Click "Resume"
4. Only one new tab pop up for one draft email (e.g. Email A)
5. Send this email out normally
6. All drafts (Email A, B, C) will disappear

After sending email A, it will remove the draft email A, however email
B & C are removed together with email A unexpectedly.