3941

Even though the bug of commit 3938 is now fixed, I'm still trying to
track down why the failure looked different on the fake screen than on
the real one. Snapshot as I try to track down the difference.

One key lesson is that the approach of commit 3860 -- updating the
cursor before rather than after printing each character -- turns out to
be untenable. A sequence of `print` followed by `cursor-position` needs
to behave the same as the real screen.

But it's still not clear how the real screen. When you get to the end of
a line the cursor position wraps after print to the left margin (column
0) on the next row. When you get to the bottom right the cursor position
wraps to the *bottom left* margin. How the heck does it know to scroll
on the next print, then? Is there some hidden state in the terminal?

1 files changed, 2 insertions, 0 deletions

diff --git a/edit/004-programming-environment.mu b/edit/004-programming-environment.mu
index 897f2923..bcd3b524 100644
--- a/edit/004-programming-environment.mu
+++ b/edit/004-programming-environment.mu
@@ -447,6 +447,7 @@ def render-recipes screen:&:screen, env:&:environment, render-editor:render-reci
   clear-screen-from screen, row, left, left, right
   #
   assert-no-scroll screen, old-top-idx
+  stash [render recipes done]
 ]
 
 # replaced in a later layer
@@ -467,6 +468,7 @@ def render-sandbox-side screen:&:screen, env:&:environment, render-editor:render
   clear-screen-from screen, row, left, left, right
   #
   assert-no-scroll screen, old-top-idx
+  stash [render sandbox side0 done]
 ]
 
 def update-cursor screen:&:screen, recipes:&:editor, current-sandbox:&:editor, sandbox-in-focus?:bool, env:&:environment -> screen:&:screen [