Copy-Paste of a picture from Windows Explorer to a new E-Mail does not always insert it as attachment, but inline

When I go to Windows Explorer and copy a picture file (e. g. png, jpg…) to the clipboard [ctrl+c],
and then open up a new e-mail-windows in em client, click into the mail body, and PASTE from clipboard [ctrl+v], 
sometimes em client attaches the picture as an attachment (what i prefer):

But in some cases it does not, and puts it into the mail body (inline) instead (what I do not prefer):

How can I prevent em Client from inserting the picture (png, jpg … file) inline ?

I’ve reported this issue to the developers, I understand that this can occur when you’re drag and dropping the file onto the email, you could avoid this by using the “attachment” option while composing a new message.
If you add the attachment manually via this button in the toolbar, the file should be always displayed in the attachment area.

But we’re reviewing this issue and hopefully can make a fix for the issue in future releases.

Thank you for pointing this out to us,