Hyprland How to create different window class

Creating different window classes in Hyprland:

• So let's say that you are trying to create a window class for alacritty to open only with a special keybinding. So let's say that you have your standard alacritty and you want it to open floating with a different window color, in a precize size and position, with a different border colour when you press a different keybinding.
• Let's say that:
  • SUPER+ENTER = Opens normal Alacritty
  • SUPER+SHIFT+ENTER = Opens floating Alacritty

How to do?

1. Create the keybinding with a new class name inside the hyprlnd configuration file. For example do this:
   • bind = $mainMod SHIFT, RETURN, exec, alacritty --class floating
     So the key binding above, will open Alacritty, instead of it's usual Alacritty class, it will open it with the class named floating.
2. Then create window rules for that class. For example:
   • windowrulev2 = float,class:floating
   • windowrulev2 = size 500 450,class:floating
   • windowrulev2 = center(1),class:floating
   • windowrulev2 = bordercolor rgb(f38ba8),class:floating
   • windowrulev2 = bordersize 7,class:floating
     So with the example above, when you press super+enter, Alacritty will open normally. If you press super+shift+enter, it will open floating, with 500px of width and 450px of height, in the center of the screen, with 7 (pixels?) border.

Note:

• When you are defining your window rules and typing the class names, you can type them in two ways:
  1. windowrulev2 = float, class:floating
  2. windowrulev2 = float, class:^(floating)
     They both seem to work. I don't know the difference. Find out.

Note 2:

It is not really related, but if you want, in the example above, want the floating Alacritty terminal to have different colours...etc, you can create a second configuration file in the ~/.config/alacritty/ folder and name it to something else than the default one. Then you can launch the alternative Alacritty with the second config file with the --config-file <path> flag. Let's say that the second config file is called alacritty-floating.toml, then you can set the keybinding in the hyprland config file this way:
bind = $mainMod SHIFT, RETURN, exec alacritty --class floating --config-file ~/.config/alacritty/alacritty-floating.toml