new parameter for sendshortcut to filter layer

[falood]

currently the parameter of sendshortcut is mod, key[, window], but some applications are not window, it's a layer(like vicinae)
vicinae doesn't have build in keybind, so I need to map ctrl + n to down.
I tried CTRL, n, sendshortcut, , down, which works well, but it's for all applications, need a way to filter it for vicinae layer only