new file mode 100644
--- /dev/null
+++ b/src/testdir/test108.ok
@@ -0,0 +1,84 @@
+
+
+
+- show backtrace:
+
+  2 function Foo[2]
+  1 Bar[2]
+->0 Bazz
+line 2: let var3 = "another var"
+
+show variables on different levels:
+
+6
+  2 function Foo[2]
+->1 Bar[2]
+  0 Bazz
+line 2: let var3 = "another var"
+3
+->2 function Foo[2]
+  1 Bar[2]
+  0 Bazz
+line 2: let var3 = "another var"
+1
+
+- undefined vars:
+
+undefined var3 on former level:
+Error detected while processing function Foo[2]..Bar[2]..Bazz:
+line    3:
+E121: Undefined variable: var3
+E15: Invalid expression: var3
+here var3 is defined with "another var":
+another var
+
+undefined var2 on former level
+Error detected while processing function Foo[2]..Bar:
+line    3:
+E121: Undefined variable: var2
+E15: Invalid expression: var2
+here var2 is defined with 10:
+10
+
+- backtrace movements:
+
+  1 function Foo[2]
+->0 Bar
+line 3: End of function
+
+next command cannot go down, we are on bottom
+
+frame is zero
+
+next command cannot go up, we are on top
+
+frame at highest level: 1
+->1 function Foo[2]
+  0 Bar
+line 3: End of function
+fil is not frame or finish, it is file
+"[No Name]" --No lines in buffer--
+
+- relative backtrace movement
+
+  1 function Foo[2]
+->0 Bar
+line 3: End of function
+->1 function Foo[2]
+  0 Bar
+line 3: End of function
+
+- go beyond limits does not crash
+
+frame at highest level: 1
+->1 function Foo[2]
+  0 Bar
+line 3: End of function
+frame is zero
+  1 function Foo[2]
+->0 Bar
+line 3: End of function
+
+- final result 19:
+19
+