The Text Area is where the messages are shown.
See also Messages Options, Inline Images Options.
Selecting text then releasing the mouse will automatically copy the text to the clipboard.
This behavior can be changed in the Messages Options.
Note: for technical reasons, it's not possible to select text while scrolling.
Various things are clickable as links such as nicks, channel names and regular links.
Double-clicking a nick opens a private window with that nick, this behavior can be changed in Options -> Mouse.
Right-clicking a nick opens the scripted Nicklist menu for this nick.
Double-clicking a channel name joins that channel.
Right-clicking a channel name opens the scripted ChannelLink menu for this channel name.
Double-clicking a link opens the link in your default browser or your custom browser set in Options -> Links, it can also be set to open by single clicking.
Right-clicking a channel name opens the scripted Link menu for this link.
Double-clicking in any other area opens the Channel Editor, this behavior can be changed in Options -> Mouse.
Right-clicking in any other area opens the scripted Channel menu for the current channel.
The links colors and font weights can be changed in Options -> Fonts/Colors.
All the menus can be customized in the Menu Editor.
It is possible for the Text Area to show inline images, see Inline Images Options for more information.
Note: the Text Area is not a webbrower, it cannot show videos or html previews. it's like a notepad with colors.
The background color and all message colors can be changed in Options -> Colors.
The font can be changed in Options -> Fonts & Sizes or by using the /font command.
It can also be changed per window by right-clicking the window in the Switchbar or Treebar then clicking Change Font.
A background image for the Text Area can be set in Options -> Backgrounds or by using the /background command.