Photoshop scripting; dialogue box to open multiple documents, but getting "undefined"

I have a dialogue box that allows the user to browse for one PSD file and then to browse for multiple TIF files. When browsing for multiple TIF files, the text in the edittext box comes out as undefined. Where as, if I just remove the ability to select multiple files, it works.

var dlg = new Window('dialog', 'PSD Creator', [100, 100, 500, 550] );  

dlg.pnl_browse = dlg.add('panel', [10, 10, 390, 150], 'Browse');
    dlg.pnl_browse.txt_staticPSD = dlg.pnl_browse.add('statictext' , [15, 10, 375, 30],'Select the project images folder:');
    dlg.pnl_browse.btn_browsePSD = dlg.pnl_browse.add ('button', [15, 35, 60, 60], '...');
    dlg.pnl_browse.txt_editPSD = dlg.pnl_browse.add('edittext' , [65, 35, 365, 55],'<Select the project images folder>');
    dlg.pnl_browse.txt_staticTIFF = dlg.pnl_browse.add('statictext' , [15, 70, 375, 90],'Select the folder where you TIFF images are:');
    dlg.pnl_browse.btn_browseTIFF = dlg.pnl_browse.add ('button', [15, 95, 60, 120], '...');
    dlg.pnl_browse.txt_editTIFF = dlg.pnl_browse.add('edittext' , [65, 95, 365, 120],'<Select the folder where you TIFF images are>');    

dlg.btn_ok = dlg.add ('button', [70,400,190,430], 'ok');
dlg.btn_cancel = dlg.add ('button', [210,400,320,430], 'cancel');


dlg.pnl_browse.btn_browsePSD.onClick = function ()  {   
    selectFilePSD = File.openDialog("Please select your template file.","*.psd");   
        if(selectFilePSD != null) dlg.pnl_browse.txt_editPSD.text =  decodeURI(selectFilePSD.fsName); 
}


dlg.pnl_browse.btn_browseTIFF.onClick = function ()  {   
    selectFileTIFF = File.openDialog("Please select your tiff images.","*.TIF; *TFF", true);  
        if(selectFileTIFF != null) dlg.pnl_browse.txt_editTIFF.text =  decodeURI(selectFileTIFF.fsName); 
 }       

dlg.btn_ok.onClick = function () {

        dlg.close()
        open (selectFilePSD);
        open (selectFileTIFF);


}

dlg.center(); 

dlg.show();

Looks like the problem is that you need to have an array to hold the files selected by the user. With that knowledge the rest of the code is reworked accordingly. Different cases were added to react to different possibilities (whether or not the array contained multiple values) and then it was just a matter of opening all the files in the array with a for loop! Hope this helps:

var dlg = new Window('dialog', 'PSD Creator', [100, 100, 500, 550] );
var selectFileTIFF = [];

dlg.pnl_browse = dlg.add('panel', [10, 10, 390, 150], 'Browse');
    dlg.pnl_browse.txt_staticPSD = dlg.pnl_browse.add('statictext' , [15, 10, 375, 30],'Select the project images folder:');
    dlg.pnl_browse.btn_browsePSD = dlg.pnl_browse.add ('button', [15, 35, 60, 60], '...');
    dlg.pnl_browse.txt_editPSD = dlg.pnl_browse.add('edittext' , [65, 35, 365, 55],'<Select the project images folder>');
    dlg.pnl_browse.txt_staticTIFF = dlg.pnl_browse.add('statictext' , [15, 70, 375, 90],'Select the folder where you TIFF images are:');
    dlg.pnl_browse.btn_browseTIFF = dlg.pnl_browse.add ('button', [15, 95, 60, 120], '...');
    dlg.pnl_browse.txt_editTIFF = dlg.pnl_browse.add('edittext' , [65, 95, 365, 120],'<Select the folder where you TIFF images are>');    

dlg.btn_ok = dlg.add ('button', [70,400,190,430], 'ok');
dlg.btn_cancel = dlg.add ('button', [210,400,320,430], 'cancel');


 dlg.pnl_browse.btn_browsePSD.onClick = function ()  {   
selectFilePSD = File.openDialog("Please select your template file.","*.psd");   
        if(selectFilePSD != null) dlg.pnl_browse.txt_editPSD.text = decodeURI(selectFilePSD.fsName); 
}


dlg.pnl_browse.btn_browseTIFF.onClick = function ()  {   
selectFileTIFF = File.openDialog("Please select your tiff images.","*.TIF; *TFF", true); 

    //selectFileTIFF is an array  thus you must loop through each selected file
    //you will need a String variable to appened the name of each file for your ScriptUI panel 
    if( selectFileTIFF.length != 0 ) {
        if( selectFileTIFF.length > 1 ) {
            dlg.pnl_browse.txt_editTIFF.text = selectFileTIFF.length + " items selected";
        } else {
            dlg.pnl_browse.txt_editTIFF.text = decodeURI( selectFileTIFF[0].fsName );
        } //end else
    } //end if
 } //end func      

dlg.btn_ok.onClick = function () {

        dlg.close()
        open (selectFilePSD);

        //must open each file is selectFileTIFF array
        for ( i = 0; i < selectFileTIFF.length; i++ ) {
        open (selectFileTIFF[i]);
        }


}

dlg.center(); 

dlg.show();