Current behavior

with collapsible true set on a borderlayout region.
If the region is closed:
-click on the region bar outside of the [>] / [v] icon : slide in the region (preview), clicking on other components will cause the region to close.
-click on the [>] / [v] icon : open the region (permanently, clicking on other components will not cause the region to close)

Feature behavior

Give the ability to choose slide, open or both effects for collapsed borderlayout, either in collapsible or in separate attributes.
Possibles syntaxes could be one of:

• separate attributes, slidable and openable (must find better names) requier collapsible, or will be ignored
  <east collapsible="true" slidable="false" openable="true">

• separate attributes, collapsible implicite if attributes are set.
  <east [collapsible="true" implicit if slidable or openable] slidable="false" openable="true">

• collapsible accepts String [true(i.e. both) | false | slide | open]
  <east collapsible="true" [implicit slide and open]>
  <east collapsible="slide" [implicit not openable]>

Workaround

Use borderlayout region isSlide / setSlide and onSlide events to call setOpen onSlide [if data:true]