If I understand your first question correctly, you want to increase the SplitBar's size. If so, this could be configured through the Spliter's SplitBarsSize
If you choose this approach most probably you will need to overwrite some of the SplitBar's CSS styles, in order to provide you custom image for its background.
Another option is to change the skin of the Splitter with one, which has bigger SplitBar by design. Such skins are BlackMetroTouch
Regarding your second question - I am afraid that I was not able to reproduce the shown in the attached screenshot issue with the provided code snippet. For your convenience I am attaching my test project - could you reproduce the save problem with it? If no - could you modify it up to a point where the problem occurs and send it back so we could examine it further?
Looking forward to hearing from you,
the Telerik team
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