JS CS3 Change geometricBounds

Question

Hi
When I run:
app.selection[0].geometricBounds = [0,0,10,10];
everything works as expected.
I only want to change the width so I tried:
app.selection[0].geometricBounds[3] += 10;
or
app.selection[0].geometricBounds[3] = app.selection[0].geometricBounds[3] + 10;
nothing changes and no error message appears.
I solved it in the following clumsy way eventually:
a = app.selection[0].geometricBounds[0];
b = app.selection[0].geometricBounds[1];
c = app.selection[0].geometricBounds[2];
d = app.selection[0].geometricBounds[3] + 10;
app.selection[0].geometricBounds = [a,b,c,d];
So it finally kind of works but it leaves me scratching my head. Is this really the way to do it?
Thanks for clarification
weller

Answer 1

I would do it this way:
myBounds = app.selection[0].geometricBounds;
myBounds[3] = myBounds[3] + 10;
app.selection[0].geometricBounds = myBounds;
The point is that because the property is an array, you must set it with an array -- if you try to manipulate a member of the array, what happens is that ExtendScript creates a temporary version of the array, manipulates that and it is left hanging out there with no effect.
Dave