Underline and Highlight Annotation on blank spaces

Hi,
I am facing a problem that on selecting underline or highlight tool when I perform drag operation on blank spaces in pdf, it performs annotation on nearest text found to the touch.


CASE:
There is only one line of text on top of a page and remaining page is empty.
If I select an underline tool and use it at the bottom(blank space) of the page, it underlines the text available on top of the page.

same is the case with highlight.

Please suggest the resolution.

Thanks.

no ideas about blank char.
logic for AddAnnotMarkup method are wrapped in native codes.

another way is using AddAnnotMarkup( Matrix mat, float[] rects, int type )
but, you shall manage all rects from char rect by yourself.

see the video for description:
www.dropbox.com/s/ldy6e0yzhsu4zq0/video.mp4

Hello,
Have you guys watched the video? please suggest any resolution for this problem.

Hello,
Are you guys looking into the issue? please resolve it as soon as possible.

Any solution guys? I am in a big problem because of it.
Please resolve it ASAP.