I'm trying to keep people from pasting pictures and increasing font sizes in the chat. I know i can remove the font size option but users can still paste pictures and bigger fonts into the chat. How can I totally filter/disable that feature?

Yes, it's possible.

 

Please open the following file: ChatUI.xml.

 

And find the following code:

 

    if(Html_IsWinIE)
    {
     box=ChatUI_CreateWinIEInputElement();
    }
    else
    {
     box=ChatUI_CreateInputTextArea();
    }

 

And change it to:

 

 

That will resolve the problems.