Resizing vertically FlowLayoutPanel on Paint Event Handler??

Question

I am creating a Office 2010 Add In which should behave like Toolbar available in Word 2003.

I should be able to resize Custom Task Pane when it is in floating Mode.

In Word 2003 we can use CommandBar class to accomplish this functionality but not in Word 2010.

I have created a add in for Woed 2010 in which I have a Custom Task Pane which contains controls in following hierarchy.

Custom Task Pane

        USer Control

                Flow Layout Panel 

                        ToolStrip

                                ToolStripButton

I wrote a Paint Event of Flow Layout Panel.

    flow.Paint +=new PaintEventHandler(flow_Resize);

I am able to resize the Custom Task Pane from left and right side but not from Top or Bottom when it is Floating. Please help.