FormText.paint(): don't pass (0,0) to Image on Linux

Fixes #3087

Author: iloveeclipse

bundles/org.eclipse.ui.forms/src/org/eclipse/ui/forms/widgets/FormText.java

@@ -20,6 +20,7 @@
 import java.util.Hashtable;
 
 import org.eclipse.core.runtime.ListenerList;
+import org.eclipse.jface.util.Util;
 import org.eclipse.swt.SWT;
 import org.eclipse.swt.SWTException;
 import org.eclipse.swt.accessibility.ACC;
@@ -1555,6 +1556,10 @@ private void paint(PaintEvent e) {
 		gc.setForeground(getForeground());
 		gc.setBackground(getBackground());
 		Point size = getSize();
+		if (size.x == 0 && size.y == 0 && Util.isLinux()) {
+			// On Linux, the size may be 0 and cause errors on Image creation.
+			size = new Point(1, 1);
+		}
 		repaint(gc, 0, 0, size.x, size.y);
 	}