adds blank entry for waveform viewer

plugins/com.minres.scviewer.database/src/com/minres/scviewer/database/BlankWaveform.java

@@ -0,0 +1,104 @@
+package com.minres.scviewer.database;
+
+import java.beans.PropertyChangeListener;
+import java.util.ArrayList;
+import java.util.List;
+
+public class BlankWaveform implements IWaveform {
+
+	@Override
+	public void addPropertyChangeListener(PropertyChangeListener l) {
+	}
+
+	@Override
+	public void removePropertyChangeListener(PropertyChangeListener l) {
+	}
+
+	@Override
+	public String getFullName() {
+		return "";
+	}
+
+	@Override
+	public String getName() {
+		return "";
+	}
+
+	@Override
+	public void setName(String name) {
+	}
+
+	@Override
+	public void setParent(IHierNode parent) {
+	}
+
+	@Override
+	public IHierNode getParent() {
+		return null;
+	}
+
+	@Override
+	public List<IHierNode> getChildNodes() {
+		return new ArrayList<>();
+	}
+
+	@Override
+	public void addChild(IHierNode child) {
+	}
+
+	@Override
+	public IDerivedWaveform deriveWaveform() {
+		return null;
+	}
+
+	@Override
+	public int compareTo(IHierNode o) {
+		return 1;
+	}
+
+	@Override
+	public long getId() {
+		return 0;
+	}
+
+	@Override
+	public boolean isSame(IWaveform other) {
+		return false;
+	}
+
+	@Override
+	public IEventList getEvents() {
+		return new EventList();
+	}
+
+	@Override
+	public IEvent[] getEventsAtTime(long time) {
+		return new IEvent[0];
+	}
+
+	@Override
+	public IEvent[] getEventsBeforeTime(long time) {
+		return new IEvent[0];
+	}
+
+	@Override
+	public WaveformType getType() {
+		return WaveformType.BLANK;
+	}
+
+	@Override
+	public String getKind() {
+		return "BLANK";
+	}
+
+	@Override
+	public int getRowCount() {
+		return 1;
+	}
+
+	@Override
+	public int getWidth() {
+		return 0;
+	}
+
+}

plugins/com.minres.scviewer.database/src/com/minres/scviewer/database/WaveformType.java

@@ -20,5 +20,7 @@ public enum WaveformType {
 	/** The transaction. */
 	TRANSACTION,
 	/** The filter. */
-	FILTER
+	FILTER,
+	/** The blank line. */
+	BLANK
 }