wm: keep windows in place when the console scrolls beneath them

The console's batched scroll (gop::shift_up_n) shifts the whole shared
shadow, which dragged any composited window pixels up with it.  Add a
scroll hook so the window manager re-composites every visible window
after a console scroll, restoring them at their fixed positions.

1 files changed, 2 insertions, 7 deletions

diff --git a/rsnix/src/vt.rs b/rsnix/src/vt.rs
index c5fc5fd..4ef568d 100644
--- a/rsnix/src/vt.rs
+++ b/rsnix/src/vt.rs
@@ -458,13 +458,7 @@ fn put_byte(b: u8) {
 }
 
 fn param(i: usize, default: usize) -> usize {
-    unsafe {
-        if i < NPARAMS {
-            PARAMS[i]
-        } else {
-            default
-        }
-    }
+    unsafe { if i < NPARAMS { PARAMS[i] } else { default } }
 }
 
 /// Place a printable glyph at the cursor and advance (wrapping/scrolling).
@@ -694,6 +688,7 @@ pub fn sync_scroll() {
         PENDING_SCROLLS = 0;
         LAST_SYNC_TICK = crate::interrupts::TICKS.load(core::sync::atomic::Ordering::Relaxed);
         flush();
+        gop::call_scroll_hook();
     }
 }