Hi Jay Jose,
Unfortunately, we do not have a solution to dynamically set the content panel height in RadPanelBar when it is in expolorer bar or vs2005 style modes. I suggest you use ListBar style for such scenarios because the content panel height is taking the maximum available height.
Let me explain to you using an example how the content panel height is calculated when the panelbar is in ListBar style:
Let's say that our PanelBar height is 200px. We add 5 RadPanelBarGroupElements to the panel bar Items collection. RadPanelBarGroupElement caption height is 20px. If we have 5 groups, the calculation is 5x20 = 100px. There are 100px more left for the content panel. This means that the content panel height depends on the panelbar height when it is in ListBar style mode.
I hope this helps.
Please write me back if you have more questions.
the Telerik team