Using mailto with GWT

[Harry]

I have written the following code to open my email client(outlook on
my machine) with pre-filled details when I press a Button.

Window.open("mailto:"exa...@example.com"?subject=<some
Subject>&body=" + getBody(), "_blank", "");

But when I try to return html code in the getBody() method.. it is
rendered as plain text instead of being rendered as described by the
html tags.

Also, Can I have tables, charts or images in the body? If yes, How?