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< Eclipse4‎ | API

UI Model

The UI Model is used to describe the various components of an application's User Interface. This model is an abstract definition that is rendered into reality on a particular platform through the use of a presentation engine driving a set of renderers (usually but not limited to one renderer part UI Model type.

The model itself is based on EMF. One of the things that EMF does a really good job at is allowing multiple inheritance so the basic design of the model starts with low-level components that can then be aggregated into concrete classes.

The model itself is composed from a number of different type of elements which are used to define the 'concrete' UI elements (i.e. the ones that actually get rendered).

The packages that will be promoted to API for the UI model include:


  • org.eclipse.e4.ui.model.application
  • org.eclipse.e4.ui.model.application.commands
  • org.eclipse.e4.ui.model.application.ui
  • org.eclipse.e4.ui.model.application.ui.advanced
  • org.eclipse.e4.ui.model.application.ui.basic
  • org.eclipse.e4.ui.model.fragment


Used to contain the attributes for different concepts such as label information or containment types. These will be useful when we eventually start to derive domain-specific models based on the current one.










Containment Definitions

In order to facilitate the use of Java generics each container may only contain elements of a single 'type' (interface really). These elements represent the type that is legal in a given container. In order to make an element legal for a given container add that container's type as one of the mix-ins for the class being contained.

WindowElement - Elements that can be added to a Window's list of children:

  • Part
  • PartStack
  • PartSashContainer

TrimElement - Elements that can be added to a TrimBar

  • ToolBar
  • ToolControl

PartSashContainerElement - Elements that can be added to a PartSashContainer

  • Part
  • PartStack
  • PartSashContainer (it's recursive)

StackElement - Elements that can be added to a PartStack

  • Part
  • Placeholder

To solve Bug 8009 maybe add PartSashContainer as child of PartStack or define a new element for this

Concrete Classes

These define the true UI model as used to present an applicaton. The UI Model has been broken down into a number of discrete packages, the sections below will be based on the contents of each package:

Basic UI

This package contains the most elementary of the UI components:


  MWindow Is this really useful? MTrimmedWindow without TrimElements seem to do the same thing


    MTrimBar (contained by an MTrimmedWindow but not in its list of children)





         MCompositePart Maybe we need to add this to allow nested parts (bug 396528)?



 Basic UI (Descriptors)

This Package contains the 'descriptors' for various elements. Currently only PartDescriptors are supported but over time we may well want to include other types such as PerspectiveDescriptors. Essentially this is the e4 way to capture the set of available views that a user may wish to open and from which the actual MPart can be instantiated.

MPartDescriptor This appears as if it should be part of the snippet story

+1 to merge it with snippets

Advanced UI

This package contains the elements necessary to support more complex UI's such as are required by the Eclipse IDE itself such as Perspectives and (editor) Areas.






This package contains the elements necessary to support the Commands infrastructure. Here a single command is referenced by any number of Handlers (at most one of which will be active in any given UI context.


MBindingTable Not sure we want this as API for now since we may want to combine or modify how these are used

While these are related to MBindingContext, they're not the same thing. These are flat tables of keybindings that are used for lookups.






MParameter Do we need this ?

Yes. This is used when placing a command in a menu item or keybinding, to specify the parameter (ex: Show View(Package Explorer).

Menus (and Toolbars)

This package contains the elements used to define menus, toolbars and their corresponding items. There are two flavors for the items, 'direct' and 'handled' based on wether the item is backed by a Command or not.







MMenuContribution This appears as if it should be part of the snippet story

This is a candidate for snippets if 1) we use the EMF XPath support (org.eclipse.e4.emf.xpath) to specify where they are placed and 2) the snippets are re-evaluated every time a new object is added to the model (we would have to be worried about performance).


MOpaqueMenu This is unnecessary (we can use different renderes for a standard MMenu now)

This might be replaceable with a tag. It's a placeholder for a Menu that the compatibility layer creates (and so it needs to be recognized by the renderer but not under its control).
+1 to do this via a tag as Paul suggests

MOpaqueMenuItem This is unecessary

+1 for removal

MOpaqueMenuSeparator This is unnecessary

+1 for removal

MOpaqueToolItem This is unnecessary

+1 for removal

MPopupMenu Do we need this...why does a popup menu need a context ?

Yes, we need a specialized menu that participates in the context hierarchy. A popup menu is like a child of the part it belongs to, it fills in specialized variable and state that need to be available to any commands executed from it.

MRenderedMenu This is unnecessary

This generates an SWT Menu by delegating to an IMenuCreator from the action world (via an IContextFunction). Maybe it could be replaced with a new renderer.
+1 for removal

MRenderedMenuItem This is unnecessary

+1 for removal

MRenderedToolbar This is unnecessary

+1 for removal


MToolBarContribution This appears as if it should be part of the snippet story

+1 to merge it with snippets



MTrimContribution This appears as if it should be part of the snippet story

+1 to merge it with snippets

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