A recent desktop app of mine had a line of ToolBar buttons, each with the same image, and I needed to distinguish between them. So I added a toolTip field to the fwt::Button class.

The Java implementation uses getToolTipText() / setToolTipText() on SWTs Control / ToolItem classes and the Javascript implementation simply adds a title attribute to the wrapping div elements.

Brian, I'll email you the patch - it's pretty small.

Edit

Figured I could just paste the patch here:

diff -r fdaadd1365a3 src/fwt/fan/Button.fan
--- a/src/fwt/fan/Button.fan	Wed Jul 08 14:21:11 2015 -0400
+++ b/src/fwt/fan/Button.fan	Thu Jul 09 13:16:41 2015 +0100
@@ -68,6 +68,11 @@
   native Str text
 
   **
+  ** The button's tool tip. Defaults to "".
+  **
+  native Str toolTip
+
+  **
   ** Image to display on button. Defaults to null.
   **
   native Image? image
diff -r fdaadd1365a3 src/fwt/java/ButtonPeer.java
--- a/src/fwt/java/ButtonPeer.java	Wed Jul 08 14:21:11 2015 -0400
+++ b/src/fwt/java/ButtonPeer.java	Thu Jul 09 13:16:41 2015 +0100
@@ -77,6 +77,15 @@
     public void set(Widget w, String v) { if (w instanceof Button) ((Button)w).setText(v); else ((ToolItem)w).setText(v); }
   };
 
+  // Str toolTip := ""
+  public String toolTip(fan.fwt.Button self) { return toolTip.get(); }
+  public void toolTip(fan.fwt.Button self, String v) { toolTip.set(v); }
+  public final Prop.StrProp toolTip = new Prop.StrProp(this, "")
+  {
+    public String get(Widget w) { return (w instanceof Button) ? ((Button)w).getToolTipText() : ((ToolItem)w).getToolTipText(); }
+    public void set(Widget w, String v) { if (w instanceof Button) ((Button)w).setToolTipText(v); else ((ToolItem)w).setToolTipText(v); }
+  };
+
   // Image image := null
   public fan.gfx.Image image(fan.fwt.Button self) { return image.get(); }
   public void image(fan.fwt.Button self, fan.gfx.Image v) { image.set(v); }
diff -r fdaadd1365a3 src/fwt/js/ButtonPeer.js
--- a/src/fwt/js/ButtonPeer.js	Wed Jul 08 14:21:11 2015 -0400
+++ b/src/fwt/js/ButtonPeer.js	Thu Jul 09 13:16:41 2015 +0100
@@ -67,6 +67,10 @@
 fan.fwt.ButtonPeer.prototype.text$ = function(self, val) { this.m_text = val; }
 fan.fwt.ButtonPeer.prototype.m_text = "";
 
+fan.fwt.ButtonPeer.prototype.toolTip = function(self) { return this.m_toolTip; }
+fan.fwt.ButtonPeer.prototype.toolTip$ = function(self, val) { this.m_toolTip = val; }
+fan.fwt.ButtonPeer.prototype.m_toolTip = "";
+
 fan.fwt.ButtonPeer.prototype.m_pressed = false;
 
 fan.fwt.ButtonPeer.prototype.create = function(parentElem, self)
@@ -93,7 +97,7 @@
   div.className = "_fwt_Button_ push";
   div.style.font = fan.fwt.WidgetPeer.fontToCss(
     this.m_font==null ? fan.fwt.DesktopPeer.$sysFont : this.m_font);
-
+  div.title = this.m_toolTip;
   var $this = this;
   div.onmousedown = function(event)
   {
@@ -164,6 +168,7 @@
   check.style.marginRight = "6px";
 
   var div = this.emptyDiv();
+  div.title = this.m_toolTip;
   with (div.style)
   {
     font = fan.fwt.WidgetPeer.fontToCss(this.m_font==null ? fan.fwt.DesktopPeer.$sysFont : this.m_font);
@@ -247,6 +252,7 @@
   {
     var div = this.elem.firstChild;
     div.tabIndex = this.m_enabled ? 0 : -1;
+    div.title = this.m_toolTip;
 
     // set def
     if (this.m_def == true) fan.fwt.WidgetPeer.addClassName(div, "def");
@@ -309,6 +315,7 @@
            self.m_mode == fan.fwt.ButtonMode.m_radio)
   {
     var div = this.elem;
+    div.title = this.m_toolTip;
     div.style.color = self.m_fg ? self.m_fg.toCss() : (this.m_enabled ? "#000" : "#444");
 
     // set state