Eclipse Plugin: is the debugger working?

I've written a very basic program using Eclipse plugin 2.8 nightly
(2.8.0.:r21376) (JDK 1.6.0_18 and Eclipse Gallileo 3.5 Java):

1 package com.acme
2 class Test (x: Int, y: Int) {
3 val xx = x
4 val yy = y
5 override def toString() = xx + "/" + yy
6 }
7 object TestRatio extends Application{
8 val a = new Test(3, 4)
9 println(a)
10 }

When I start the debugger there is an error: "Unable to install breakpoint
in com.acme.TestRatio due to missing line number attributes. Modify compiler
options to generate line numbers attributes" "Reason: Absent line number
information".
If I ignore the message and change to the debug perspective, the debugger
does stop at line 8, but with another error: " 'JDI thread evaluations' has
encountered a problem. Exception processing assync thread queue".

if I change lines 7,8,9 and 10 to:

7 object TestRatio extends Application{
8 val a = new Test(3, 4)
9 println(a)
10 }

I can not set the breakpoint in line 8 (although I can set a breakpoint at
line 4). The editor sets a class breakpoint at line 7.

It seems that breakpoints inside objects are not working.

If you try to avoid this and change the object to:

7 class TestRationalClass {
8 def run() {
9 val a = new Test(3, 4)
10 println(a)
11 }
12 }
13 object TestRatio extends Application{
14 val t = new TesteRatioClass()
15 t.run
16 }

Now you can toggle the breakpoint at line 9. But if you set a breakpoint at
line 5 (the override) and try to step debug (F5), the debugger issues may
errors 'JDI thread evaluations' and enters many times in the "predef.scala",
"stringbuilder.scala" and others (is there a way to keep only in your source
code? Filters are not working).

Also, when I place the cursor over a parameter (i.e, y), it doesn't show
it's value. But if I create a watch it does show the value.

I tried the same thing in 3 different computers with clean eclipse install.
Same results.

These errors seem very basic, so I suspect that maybe my Eclipse install
could have some incompatibility...

Any comment would be very welcome!

Thanks,

Marcos