[Lazarus] Docking manager implementation

[Micha Nelissen]

Reenen Laurie wrote:
> For me, all I really want that's not supported via Lazarus at the moment 
> is the % of parent statement...
> 
> So
> child1.top := 0%  (1%?)
> child1.bottom := 33%
> child2.top := 34%;
> child2.bottom := 100%;

These kind of calculations are easy in the OnResize event of the parent. 
A OnResize is also much more flexible, because you can keep some childs 
fixed and others proportional etc. Also the in between child space is 
preferred to be fixed e.g. 6 pixels or so. I think there are many 
variations on the 'proportional theme' to be liked that they cannot be 
put into a 'choose pull-down' property editor.

Micha