layout, csstree: build stacking contexts together with tree

We often redo sub-layouts in layout, and this makes stacking contexts
very hard to build reliably there.

This fixes a bug where positioned descendants of flex items would
sometimes mysteriously disappear.

1 files changed, 3 insertions, 2 deletions

diff --git a/src/server/buffer.nim b/src/server/buffer.nim
index f8ced08d..6f3e004f 100644
--- a/src/server/buffer.nim
+++ b/src/server/buffer.nim
@@ -725,9 +725,10 @@ proc maybeReshape(buffer: Buffer) =
   if document == nil or document.documentElement == nil:
     return # not parsed yet, nothing to render
   if document.invalid:
-    buffer.rootBox = document.documentElement.buildTree(buffer.rootBox,
+    let stack = document.documentElement.buildTree(buffer.rootBox,
       buffer.config.markLinks)
-    let stack = buffer.rootBox.layout(addr buffer.attrs)
+    buffer.rootBox = BlockBox(stack.box)
+    buffer.rootBox.layout(addr buffer.attrs)
     buffer.lines.render(buffer.bgcolor, stack, addr buffer.attrs, buffer.images)
     document.invalid = false
     if buffer.hasTask(bcOnReshape):