ExtCtrls

Add a splitter to a form between two aligned controls to allow users to resize the controls at runtime. The splitter sits between a control aligned to one edge of the form and the controls that fill up the rest of the client area. Give the splitter the same alignment as the control that is anchored to the edge of the form. When the user moves the splitter, it resizes the anchored control. This, in turn, changes the client area of the form, and the controls that fill up the rest of the client area resize accordingly. 

Use each control on the form as a separate pane. After each pane is placed, place a splitter with the same alignment to allow that pane to be resized. The last pane to be placed on the form should be client-aligned, so that it resizes automatically to fill up the remaining space after all other panes are resized. 

TForm 

Splitter Controls