created an attachment (id=165063)
ppt file

descriptioin:
tooltip is "null" for hyperlink in ppt 

build:
2.6.0.v20100315-1900

steps to reproduce:
1. new a label with hyperlink
2. keep tooltip as blank
3. preview in ppt

actual result:
tooltip is "null" for hyperlink in ppt 

expect result:
when tooltip is blank in hyperlink setting, actual url should be show up
fixed the problem.
verify the bug