How to automatic resize tinyMCE?

I have a TinyMCE that is set over a TextArea, and I want this editor area to ocuppy all the space of its parent div, all times.

I have a JS function that get the current space and set the textarea.style.height to it, but when I enables TinyMCE it seems to stop working.

Also, the textarea has width: 100%; it doesn't resize by HTML rendering when it's using TinyMCE too.

Any ideas?

Nowadays, you should use the autoresize plugin that comes with tinyMCE. You will have to call tinyMCE like this (jQuery version):

$('.tinymce').tinymce({
  theme : 'advanced',
  plugins : 'autoresize',
  width: '100%',
  height: 400,
  autoresize_min_height: 400,
  autoresize_max_height: 800,
});

I made the experience, that it may be helpful to manually call the resizing in the init_instance_callback to provide the correct height on init. Add this parameter to the passed options, if you need this:

init_instance_callback: function (inst) { inst.execCommand('mceAutoResize'); }

The point is that TinyMCE generates an iframe in the place of the textarea, with this ID: originalID+"_ifr", and a table originalID+"_tbl" for holding the controls and the editor area.

To make fluid width:

document.getElementById(id+'_tbl').style.width='100%'

To make fluid height:

Change dinamically document.getElementById(id+'_ifr').style.height to the height you want, through JS.
This is the script I'm using for this:

function toScreenHeight(id, minus) {
    var height;

    if (typeof(window.innerHeight) == "number") //non-IE
        height = window.innerHeight;
    else if (document.documentElement && document.documentElement.clientHeight) //IE 6+ strict mode
        height = document.documentElement.clientHeight;
    else if (document.body && document.body.clientHeight) //IE 4 compatible / IE quirks mode
        height = document.body.clientHeight;

    document.getElementById(id).style.height = (height - minus) + "px";
}

You can use the code and function calls inside onload and onresize body events.

in tinymce 3.4.6, set

width:'100%'

in init option will solve the problem.