Bug 250604 [FieldAssist] API - ContentProposalAdapter needs isShowing() method
Please implement a method ContentProposalAdapter.isShwoing(). The method should return a boolean whether the content assistant proposal popup is open or not.
bundles/org.eclipse.jface/src/org/eclipse/jface/fieldassist/ContentProposalAdapter.java
proposalTable.setRedraw(false);
					proposalTable.setItemCount(newSize);
					TableItem[] items = proposalTable.getItems();
					for (int i = 0; i < items.length; i++) {
						TableItem item = items[i];
						IContentProposal proposal = newProposals[i];
						item.setText(getString(proposal));
						item.setImage(getImage(proposal));
						item.setData(proposal);
					}
					proposalTable.setRedraw(true);
				}
				
				if (newProposals.length > 0) {
					selectProposal(0);
				} else {
					
					if (infoPopup != null) {
						infoPopup.close();
					}
				}
			}
		}
		/*
		 * Get the string for the specified proposal. Always return a String of
		 * some kind.
		 */
		private String getString(IContentProposal proposal) {
			if (proposal == null) {
				return EMPTY;