is there a way to add an apply button in command(dialog)?
I guess it depends on what you expect the behavior of the apply button to do. I was doing something recently where I wanted an apply button like Inventor has where it executes the command with the current inputs but remains running so you can continue to use it and it maintains the current settings. Unfortunately, if you look at all of Fusion's command, none of them currently use the concept of "apply" so the internals of Fusion don't currently support it.
There are a couple of potential workarounds. I wanted to have three buttons at the bottom of the dialog, "OK", "APPLY", and "CANCEL" but it's only possible to have either one or two buttons. You can however, change the text on the buttons so you could have "APPLY" and "CANCEL" buttons. However, clicking the "APPLY" will still result in the execute behavior because all you can do is change the displayed name, not the command behavior. I haven't tried this, but it might be possible to invoke the command again in the command's destroy event so it would immediately be available again.
Another option is to add a regular button using a Boolean command input to the dialog and use this as the trigger for the apply. This gets tricky because everything you do within a command is wrapped as a single undo operation so canceling the command will undo everything since the command was started, not just since the last apply. You can't have intermediate undo steps within a single command. The previous approach with re-invoking the commands solves this because the command is really run for each apply.
So both approaches are far from ideal but I think the first one is the best because it provides the best behavior form a user standpoint and would be the easiest to implement, assuming the command can execute itself as it's being destroyed.
If you're idea of "apply" is something else, then I would guess the Boolean command input is still probably the best solution.
