FFish Script runs outside Action Script and has unattached runtime environment. So you don't need to worry about the loss of synchronization with Action script.

E.g. Say you want to display a message box, if the users click the 'Ok' button, do thing 1, if the users click the 'Cancel' button, do thing 2. Let's compare the fscommand implementation and the FFish Script implementation.

// Action script code
// The "prompt" command displays a message box with the "ok" and "cancel" button
// If the "ok" button is pressed, the command sets the Action Script variable "ret" to true
// Otherwise, the variable "ret" will be set to false

fscommand("prompt", "Please choose, Ok or Cancel, ret");

if (ret)
{

do thing 1

}
else
{

do thing 2

}

// FFish Script code

var ret = Dialogs.msgBox("Please choose", "Ok or Cancel", 1);
if (ret == 1)
{

do thing 1

}
else
{

do thing 2

}

if (ret)
{

do thing 1

}
else
{

do thing 2

},

the fscommand may not have been handled yet. You have to poll the value the variable "ret" in Action script, don't call the following code until the fscommand returns. Or you can add the "do things" code in a callback function that will be called when the fscommand returns. THAT IS TO SAY, IN THIS CASE, FSCOMMANDS CANNOT WORK IN A FLUENT WAY. YOU MUST ADD SOME MEANS TO CHECK IF THE FSCOMMANDS HAVE BEEN FINISHED SUCCESSFULLY.

// Action script code
// The "prompt" command displays a message box with the "ok" and "cancel" button
// If the "ok" button is pressed, the command sets the Action Script variable "ret" to true
// Otherwise, the variable "ret" will be set to false

// Frame 1
var ret = "undefined";
fscommand("prompt", "Please choose, Ok or Cancel, ret");

// Frame 2
// Blank

// Frame 3
if (ret == "undefined") gotoAndPlay(2);

// Frame 4
if (ret)
{

do thing 1

}
else
{

do thing 2

}