messagebox — Open a message box.
    [btn] = messagebox(msg)
    [btn] = messagebox(msg, msgboxtitle)
    [btn] = messagebox(msg, msgboxtitle, msgboxicon)
    [btn] = messagebox(msg, msgboxtitle, msgboxicon)
    [btn] = messagebox(msg, msgboxtitle, msgboxicon, buttons)
    [btn] = messagebox(msg, msgboxtitle, msgboxicon, buttons, ismodal)
    Matrix of strings: the message box displays each entry of this matrix (one entry per line).
String: the title of the message box (default value is "Scilab Message").
String: the name of the icon to be displayed in the message box, its possible values are:
"error"
"hourglass"
"info"
"passwd"
"question"
"warning"
"scilab": default icon
1xn vector of strings: the names of the buttons to be displayed in the message box. By default, only one button is displayed with label "OK".
String: "modal" to create a modal dialog, any other string to create a non-modal dialog. Please note that "modal" can replace any of the other input arguments except msg (See examples).
Scalar: number of the button that the user pressed (1 is the leftmost button) for a modal dialog, 0 else.
 
// Simple example
messagebox("Single line message")
// Multi line message with title
messagebox(["Multi-line" "message"], "User defined title")
// Icon specified by th euser
messagebox("An error message", "Error", "error")
// Buttons labels + "modal" replaces title
messagebox("Have you seen this beautiful message", "modal", "info", ["Yes" "No"])
// "modal" given as fifth input argument
messagebox("An error message", "Error", "error", ["Continue" "Stop"], "modal")