pull splitting as a feature into IInlineBox

Signed-off-by: Florian Thienel <florian@thienel.org>
diff --git a/org.eclipse.vex.core/src/org/eclipse/vex/core/internal/boxes/IInlineBox.java b/org.eclipse.vex.core/src/org/eclipse/vex/core/internal/boxes/IInlineBox.java
index e074b93..2f8fcf3 100644
--- a/org.eclipse.vex.core/src/org/eclipse/vex/core/internal/boxes/IInlineBox.java
+++ b/org.eclipse.vex.core/src/org/eclipse/vex/core/internal/boxes/IInlineBox.java
@@ -10,6 +10,7 @@
  *******************************************************************************/
 package org.eclipse.vex.core.internal.boxes;
 
+import org.eclipse.vex.core.internal.core.Graphics;
 import org.eclipse.vex.core.internal.core.Rectangle;
 
 /**
@@ -37,4 +38,8 @@
 
 	boolean join(IInlineBox other);
 
+	boolean canSplit();
+
+	IInlineBox splitTail(Graphics graphics, int splittingWidth);
+
 }
diff --git a/org.eclipse.vex.core/src/org/eclipse/vex/core/internal/boxes/Square.java b/org.eclipse.vex.core/src/org/eclipse/vex/core/internal/boxes/Square.java
index fce4bce..511b56d 100644
--- a/org.eclipse.vex.core/src/org/eclipse/vex/core/internal/boxes/Square.java
+++ b/org.eclipse.vex.core/src/org/eclipse/vex/core/internal/boxes/Square.java
@@ -94,4 +94,13 @@
 		return false;
 	}
 
+	@Override
+	public boolean canSplit() {
+		return false;
+	}
+
+	@Override
+	public IInlineBox splitTail(final Graphics graphics, final int splittingWidth) {
+		throw new UnsupportedOperationException("Splitting is not supported for Square.");
+	}
 }