This setting you are pointing to is for assigning fixed sizes.
I recall a time when you could manually adjust the panel split on the fly. Sometimes I want more space on the top panel, and somethimes I want more space on the bottom panel.
You must have disabled this feature for some reason???
>>I used to be able to resize the upper and lower frame on the message area. This no longer works
>
>You may update that setting here:
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>
http://www.levelextreme.com/DataEntryMemberUpdate.aspx>
>"Upper frame height in percentage"