Create a popup window for choosing a colour
popup_color_picker(title = "Choose colourr", ...)
Title to display on popup window
other named arguments used to initialise this widget
See tcl/tk documentation for more information on this element https://www.tcl.tk/man/tcl8.6/TkCmd/chooseColor.html
if (FALSE) {
popup_color_picker(message = 'hello')
}