empty data overlay doesn't have glyph

CHANGELOG

@@ -29,6 +29,8 @@ minerva (12.3.1~beta.1) unstable; urgency=low
   * Bug fix: empty type for data overlay is allowed (#827)
   * Bug fix: genetic variants data overlay was ignoring color parameter (#827)
   * Bug fix: pathways can be drawn using glyphs (#825)
+  * Bug fix: empty background overlay doesn't show glyphs, instead standard 
+    visualization is used (#826)
 
 minerva (13.1.0~beta.0) unstable; urgency=low
   * Feature: annotators are more flexible - you can define set of input and

model-command/src/main/java/lcsb/mapviewer/commands/ColorModelCommand.java

@@ -337,6 +337,7 @@ public class ColorModelCommand extends ModelCommand {
 
     for (Element element : result.getElements()) {
       element.setColor(Color.WHITE);
+      element.setGlyph(null);
     }
     for (Reaction reaction : result.getReactions()) {
       for (AbstractNode node : reaction.getNodes()) {