Bug 36446 [Contributions] widgets: Associating Actions with Buttons
Actions can be associated with Menu items , and tool bar items using MenuManager and ToolBarManager but there is not way to associate Action with a regular button and obtaining a reference to that button the closest thing is creating an ActionContributionItem with the desired action in its constructor , then filling the parent composite with ActionContributionItem.fill(Control parent) this creats the button , but it doesn't return a reference to that button , so for example i can't give it any layout data i suggest the ActionContributionItem.fill(Control parent) returns the created widget
bundles/org.eclipse.jface/src/org/eclipse/jface/action/ActionContributionItem.java
boolean shouldBeEnabled = action.isEnabled()
							&& isEnabledAllowed();
					if (mi.getEnabled() != shouldBeEnabled) {
						mi.setEnabled(shouldBeEnabled);
					}
				}
				if (checkChanged) {
					boolean bv = action.isChecked();
					if (mi.getSelection() != bv) {
						mi.setSelection(bv);
					}
				}
				return;
			}
			if (widget instanceof Button) {
				Button button = (Button) widget;
				if (imageChanged && updateImages(false)) {
					textChanged = false; 
					
				}
				if (textChanged) {
					String text = action.getText();
					if (text == null) {
						text = ""; 
					} else {
						text = Action.removeAcceleratorText(text);
					}
					button.setText(text);
				}
				if (tooltipTextChanged) {