Text boxes created in Impress lose their "Fit height to text" setting when saved
as PowerPoint, but custom shapes retain the setting as expected.

To reproduce:

1. Create a text box and enter some text. By default, the Format > Text... >
"Fit height to text" option is checked and the "Fit width to text" option is
unchecked.
2. Create a custom shape from the Drawing toolbar. Click on the Basic Shape
button and select a Rectangle from the menu. (Don't use the rectangle button.
That creates a different type of shape.) Create a box and enter some text.
3. Select Format > Text... Then check both the "Word wrap text in shape" and the
"Resize shape to fit text" options.
4. Save as PowerPoint.
5. Open in Microsoft PowerPoint 2003 or 2007. 
6. Select text box.
7. Select Format > Text Box. In the Format Text Box dialog on the Text Box tab,
the "Resize Autoshape to fit text" option is unchecked but should be checked.
8. Select the custom shape.
9. Select Format > Text Box. In the Format Autoshape dialog on the Text Box tab,
the "Resize Autoshape to fit text" option is checked as expected.

I've attached a demo ODP file and the exported PPT file, along with some screen
shots.

The custom shape is a draw:custom-shape object in the XML. During export, a
draw:custom-shape seems to be translated to a PowerPoint Autoshape rather than a
PowerPoint Text Box. The two objects can be differentiated in PowerPoint by the
name of the Format dialog box.

The underlying style attributes for the text box (a draw:frame object containing
a draw:text-box) and the custom shape (a draw:custom-shape object) are
identical. Plus the two objects have identical fitting options in the Impress
UI. (Some aren't editable by the user depending on the object type). But the
text box loses its fitting option during export and the shape doesn't.

As an aside, text boxes first created in PowerPoint retain the fitting option in
Impress, because PowerPoint text boxes are imported as custom shapes instead of
true text boxes.

Fixing this would greatly improve workflows where presentations are authored in
Impress but later edited in PowerPoint.