This property is used in objects that can change size to fill a certain area. By setting this value you can have the object automatically grow or shrink as the form size is changed. The options are:
alBottom | Attach the object to the bottom of the form and fill from left to right side. The only change you can make is in height. |
alClient | Takes up the entire form. You can't make any changes in size other than changing the size of the underlying form. |
alLeft | Attach the object to the left side of the form and fill from top to bottom. The only change you can make is in width. |
alNone | Doesn't attach to any side, doesn't change the size of the object. This is the default value. |
alRight | Attach the object to the right side of the form and fill from top to bottom. The only change you can make is in width. |
alTop | Attach the object to the top of the form and fill from left to right side. The only change you can make is in height. |
This is similar to using the Anchors property except the object will fill a section of the form. You can also 'stack' objects that have this property. For example, you can put a TPanel at the bottom of the form using the alBottom option, then put another TPanel on top of that, again using the alBottom option. The second TPanel will not cover-up the first one you created.