Description Steve Monnier 2020-07-07 10:27:04 EDT

On a diagram editor with a custom tabbar that contributed the "Copy format" tabbar action, activating it causes the following NPE:
java.lang.NullPointerException
       at org.eclipse.gmf.runtime.diagram.ui.actions.DiagramAction.getDiagramCommandStack(DiagramAction.java:151)
       at org.eclipse.gmf.runtime.diagram.ui.actions.DiagramAction.execute(DiagramAction.java:141)
       at org.eclipse.gmf.runtime.diagram.ui.actions.DiagramAction.doRun(DiagramAction.java:104)
       at org.eclipse.gmf.runtime.common.ui.action.AbstractActionHandler.run(AbstractActionHandler.java:360)
       at org.eclipse.gmf.runtime.common.ui.action.ActionManager$1.run(ActionManager.java:226)
       at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:71)
       at org.eclipse.gmf.runtime.common.ui.action.ActionManager.run(ActionManager.java:224)
       at org.eclipse.gmf.runtime.common.ui.action.AbstractActionHandler.runWithEvent(AbstractActionHandler.java:378)
       at org.eclipse.jface.action.ActionContributionItem.handleWidgetSelection(ActionContributionItem.java:565)
       at org.eclipse.jface.action.ActionContributionItem.lambda$5(ActionContributionItem.java:436)
       ...

Steps to reproduce:
- import DATA_0020 (from the acceptance test examples or from the attached zip)
- this will import the project sample.tabbar.contributor.extension in your workspace
- in this project open the class TabbarContributorSample, in the method "getDiagramElementContributionItem" add "diagramElementContributionItems.add(createCopyFormatContribution(part)); " to the list
- launch a runtime
- open a diagram
- select an element and click on the tabbar action with the tooltip "Copy the format of the selected diagram elements"
-> It should not open a popup with just a message "null" and throw the NPE.