With the plain text the focus always ends at the end of the text

When you compose an email in plain text mode and you want to paste some text taken elsewhere, by clicking on the webtop window the focus inside the email always ends at the bottom and does not remain in the point where you left the cursor.

Steps to reproduce:

• create an email in plain text
• write a few lines of text
• move with the cursor to the beginning of the email
• copy text from a different browser window
• return to the webtop window and paste the copied text

Expected behaviour:

• the text is copied to the point where you left the cursor

Actual behaviour:

• the text is copied at the end of the text (the focus moves to the bottom)

Note:
with the HTML composition the problem does not occur