フレームサイズの取得

[JavaScript]

var frame = app.activeDocument.selection[0];
var y  = frame.visibleBounds[0];  //左上 y
var x  = frame.visibleBounds[1];  //左上 x
var y1 = frame.visibleBounds[2];  //右下 y1
var x1 = frame.visibleBounds[3];  //右下 x1

[VBScript]

Set app = CreateObject("InDesign.Application")
Set frame = app.activeDocument.selection(1)
y  = frame.visibleBounds(0)  '左上 y
x  = frame.visibleBounds(1)  '左上 x
y1 = frame.visibleBounds(2)  '右下 y1
x1 = frame.visibleBounds(3)  '右下 x1

※参考
　現在のフレームサイズから縦サイズ+10mm変更の場合

[JavaScript]

frame.visibleBounds = [ frame.visibleBounds[0],frame.visibleBounds[1],frame.visibleBounds[2]+10,frame.visibleBounds[3] ];

[VBScript]

frame.visibleBounds = Array( frame.visibleBounds(0),frame.visibleBounds(1),frame.visibleBounds(2)+10,frame.visibleBounds(3) )