All details are based on the result from the Microsoft Windows XP.
1.1 Layout setting by Gridding
In general, we can create layout by setting the layout argument in a frame or a panel, for example,
gui = do f <- frame [ text := "Layout" ] p <- panel f  b <- button p [ text := "button" ] set f [ layout := margin 2 $ container p $ floatCenter $ widget b , clientSize := sz 100 100 ]
I will call this Layout setting by Gridding.
Gridding means using the layout function, such as grid, row, column etc, to set the layout.
1.2 Layout setting by Positioning
Also, we could set the layout by another way, Layout setting by Positioning
gui = do f <- frame [ text := "Layout" , clientSize := sz 100 100 ] p <- panel f [ clientSize := sz 98 98, , position := pt 2 2 ] b <- button p [ text := "button" , position := pt 45 45 ]
The result of both examples are about the same, only the button position has a bit different. (Please measure the exact position by yourself). By this way, we can have more flexible layout rather than limited the layout by grids.
2 Layout Reconfiguration
We can also re-configure the layout by just simply re-assign a new layout value to the layout. But remember, do not assign the same tab to the layout twice, it will append the same tab to the notebook. To prevent this, assign an empty list to the notebook
f <- frame [ text := "Layout" ] nb <- notebook f  set f [ layout := tabs nb  ]
3 See Also
Button Sizing Problem - It has problems to set the size of button