Fix https://forum.plantuml.net/15211

src/net/sourceforge/plantuml/project/GanttDiagram.java

@@ -405,14 +405,15 @@ public class GanttDiagram extends TitledDiagram implements ToTaskDraw, WithSprit
 						task.getStyleBuilder(), getSkinParam().getIHtmlColorSet());
 			} else {
 				final TaskImpl tmp = (TaskImpl) task;
+				final String disp = hideRessourceName ? tmp.getCode().getSimpleDisplay() : tmp.getPrettyDisplay();
 				if (tmp.isDiamond()) {
-					draw = new TaskDrawDiamond(timeScale, y, tmp.getPrettyDisplay(), getStart(tmp), getSkinParam(),
+					draw = new TaskDrawDiamond(timeScale, y, disp, getStart(tmp), getSkinParam(), task, this,
-							task, this, task.getStyleBuilder(), getSkinParam().getIHtmlColorSet());
+							task.getStyleBuilder(), getSkinParam().getIHtmlColorSet());
 				} else {
 					final boolean oddStart = printStart != null && min.compareTo(getStart(tmp)) == 0;
 					final boolean oddEnd = printStart != null && max.compareTo(getEnd(tmp)) == 0;
-					draw = new TaskDrawRegular(timeScale, y, tmp.getPrettyDisplay(), getStart(tmp), getEnd(tmp),
+					draw = new TaskDrawRegular(timeScale, y, disp, getStart(tmp), getEnd(tmp), oddStart, oddEnd,
-							oddStart, oddEnd, getSkinParam(), task, this, getConstraints(task), task.getStyleBuilder(),
+							getSkinParam(), task, this, getConstraints(task), task.getStyleBuilder(),
 							getSkinParam().getIHtmlColorSet());
 				}
 				draw.setColorsAndCompletion(tmp.getColors(), tmp.getCompletion(), tmp.getUrl(), tmp.getNote());
@@ -785,4 +786,11 @@ public class GanttDiagram extends TitledDiagram implements ToTaskDraw, WithSprit
 
 	}
 
+	private boolean hideRessourceName;
+
+	public CommandExecutionResult hideRessourceName() {
+		this.hideRessourceName = true;
+		return CommandExecutionResult.ok();
+	}
+
 }

src/net/sourceforge/plantuml/project/GanttDiagramFactory.java

@@ -50,6 +50,7 @@ import net.sourceforge.plantuml.project.command.CommandColorTask;
 import net.sourceforge.plantuml.project.command.CommandFootbox;
 import net.sourceforge.plantuml.project.command.CommandGanttArrow;
 import net.sourceforge.plantuml.project.command.CommandGanttArrow2;
+import net.sourceforge.plantuml.project.command.CommandHideRessourceName;
 import net.sourceforge.plantuml.project.command.CommandLabelOnColumn;
 import net.sourceforge.plantuml.project.command.CommandLanguage;
 import net.sourceforge.plantuml.project.command.CommandNoteBottom;
@@ -109,6 +110,7 @@ public class GanttDiagramFactory extends PSystemCommandFactory {
 		cmds.add(new CommandNoteBottom());
 		cmds.add(new CommandFootbox());
 		cmds.add(new CommandLabelOnColumn());
+		cmds.add(new CommandHideRessourceName());
 
 		// cmds.add(new CommandScaleWidthAndHeight());
 		// cmds.add(new CommandScaleWidthOrHeight());

src/net/sourceforge/plantuml/project/command/CommandHideRessourceName.java

@@ -0,0 +1,68 @@
+/* ========================================================================
+ * PlantUML : a free UML diagram generator
+ * ========================================================================
+ *
+ * (C) Copyright 2009-2020, Arnaud Roques
+ *
+ * Project Info:  http://plantuml.com
+ * 
+ * If you like this project or if you find it useful, you can support us at:
+ * 
+ * http://plantuml.com/patreon (only 1$ per month!)
+ * http://plantuml.com/paypal
+ * 
+ * This file is part of PlantUML.
+ *
+ * PlantUML is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * PlantUML distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
+ * License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
+ * USA.
+ *
+ *
+ * Original Author:  Arnaud Roques
+ * 
+ *
+ */
+package net.sourceforge.plantuml.project.command;
+
+import net.sourceforge.plantuml.LineLocation;
+import net.sourceforge.plantuml.command.CommandExecutionResult;
+import net.sourceforge.plantuml.command.SingleLineCommand2;
+import net.sourceforge.plantuml.command.regex.IRegex;
+import net.sourceforge.plantuml.command.regex.RegexConcat;
+import net.sourceforge.plantuml.command.regex.RegexLeaf;
+import net.sourceforge.plantuml.command.regex.RegexResult;
+import net.sourceforge.plantuml.project.GanttDiagram;
+
+public class CommandHideRessourceName extends SingleLineCommand2<GanttDiagram> {
+
+	public CommandHideRessourceName() {
+		super(getRegexConcat());
+	}
+
+	static IRegex getRegexConcat() {
+		return RegexConcat.build(CommandHideRessourceName.class.getName(), RegexLeaf.start(), //
+				new RegexLeaf("hide"), //
+				RegexLeaf.spaceOneOrMore(), //
+				new RegexLeaf("ressources?"), //
+				RegexLeaf.spaceOneOrMore(), //
+				new RegexLeaf("names?"), //
+				RegexLeaf.end()); //
+	}
+
+	@Override
+	protected CommandExecutionResult executeArg(GanttDiagram diagram, LineLocation location, RegexResult arg) {
+		return diagram.hideRessourceName();
+	}
+
+}

src/net/sourceforge/plantuml/version/Version.java

@@ -80,7 +80,7 @@ public class Version {
 	}
 
 	public static int beta() {
-		final int beta = 5;
+		final int beta = 6;
 		return beta;
 	}