Placement of Ctrls within its parent is determined by logical positions. Logical position alow more complex placement relative to parent Ctrl rectangle. There are four types of horizontal logical positions:
left - in this case, logical position determines distance from left edge of parent rectangle and horizontal size.
size - logical position determines distance from both left and right edges of parent Rect
right - logical position determines horizontal size and distance from right edge of Rect.
center - logical position determines distance from center horizontal size.
Vertical logical positions are equivalent.
Each time parent Ctrl changes its layout (usually as result of creation or resizing), pixel positions of all Ctrls are recomputed based on logical positions.
Another issue that is related to positions is layout zooming. The problem here is that application can use font of different size or type than standard one used in layout designer when designing layout. That is why layout logical position need to be zoomed. Zoom factor is determined by ratio of text "OK Cancel Exit Retry" in runtime standard font size to Size(99, 13) - size of this text using standard font.
Zooming layout positions is done using placement methods with Z suffix (like LeftPosZ etc...).