Eclipse Plugin: Debug: Step Over (F6) behavior and Variable Tooltips

Using the following code, with a breakpoint set at line 2:

1 class H (x: Int) {
2 val xx = x
3 val yy = xx
4 val zz = xx + yy
5 val ww = zz + yy + xx
6 }
7
8 object Hello extends Application {
9 val a = new H(4)
10 }

When the debugger stops at line 2, if you place the cursor over the "x"
parameter the tooltip shows the value of "xx" instead of the "x". (The
variable view show the "x" correctly)

Typing F6 (Step Over), the current line goes to line 3 as expected, but
again, placing the cursor over the "xx", the tooltip shows the value of
"yy".
Another F6 makes the cursor go to the line 2, instead of the next line (line
5).

The expected sequence using F6 should (I think) be: Lines: 2, 3, 4, 5
But the real sequence is: 2, 3, 2, 3, 4, 2, 4, 5, 2, 5, 9 .

I think the debugger should stop at line 6, before returning to line 9.

When the current line is line 5, placing the cursor over "xx", the tooltip
shows only "xx: Int" (no value) and over "yy", shows "yy: Int". Over zz,
shows: "ww=0".

Is this a bug?