Why is the smplayer class not working in i3?

Question

linux

Good afternoon.
I am using i3wm windows in xubuntu 18.04.
There is a problem, when I start smplayer, I can not determine it on the first workspace.
For example, there is visual studio code and cherrytree, it works for them.

assign [class="Smplayer"] $workspace4
assign [class="Code"] $workspace2
assign [class="Cherrytree"] $workspace3

But for smplayer - no.
What's wrong, or how to define class names for an application.
I determine from the search bar.
Thanks in advance.

Answer 1

To get the class and instance, you can use xprop. After clicking on the window, you will see the following output:
xprop:
WM_CLASS(STRING) = "irssi", "URxvt"
The first part of the WM_CLASS is the instance ("irssi" in this example), the second part is the class("URxvt" in this example).

From here: https://i3wm.org/docs/userguide.html
Item 4.17. Automatically putting clients on specific workspaces.
That is, first install xprop. Start smplayer. In the console run xprop and just click on the smplayer window. Xprop will display all the info.