graflow: replaced fixed by absolute in subflows

bzGraflow.js

@@ -253,8 +253,10 @@ class BZgraflow extends Buildoz{
         // Initial transform so the full-size child "fits" inside the node
         const sx0 = nodeBB.width / parentBB.width
         const sy0 = nodeBB.height / parentBB.height
-        const tx0 = nodeBB.left - parentBB.left
-        const ty0 = nodeBB.top  - parentBB.top
+        // When the host graflow is scrollable, nodeBB is viewport-relative while the invading child
+        // is positioned inside `this` (absolute/inset=0). Add scroll offsets to keep coordinates consistent.
+        const tx0 = (nodeBB.left - parentBB.left) + (this.scrollLeft || 0)
+        const ty0 = (nodeBB.top  - parentBB.top)  + (this.scrollTop  || 0)
 
         // Inline "scaler" (shadow styles don't apply to the child element)
         childEl.style.transformOrigin = 'top left'
@@ -294,12 +296,12 @@ class BZgraflow extends Buildoz{
     }
 
     invade(oldEl, newEl){
-        const r = oldEl.getBoundingClientRect()
-        newEl.style.position = 'fixed'  //TODO This is bad: not scroll-proof !!
-        newEl.style.left = r.left + 'px'
-        newEl.style.top  = r.top  + 'px'
-        newEl.style.width  = r.width + 'px'
-        newEl.style.height = r.height + 'px'
+        // Scroll-proof overlay: position inside oldEl so it follows oldEl scrolling.
+        // Ensure oldEl is a positioning context.
+        const pos = getComputedStyle(oldEl).position
+        if(pos === 'static') oldEl.style.position = 'relative'
+        newEl.style.position = 'absolute'
+        newEl.style.inset = '0'
         newEl.style.display = 'block'
         oldEl.appendChild(newEl)
     }
@@ -322,8 +324,8 @@ class BZgraflow extends Buildoz{
         const parentBB = this.getBoundingClientRect()
         const sx0 = nodeBB.width / parentBB.width
         const sy0 = nodeBB.height / parentBB.height
-        const tx0 = nodeBB.left - parentBB.left
-        const ty0 = nodeBB.top  - parentBB.top
+        const tx0 = (nodeBB.left - parentBB.left) + (this.scrollLeft || 0)
+        const ty0 = (nodeBB.top  - parentBB.top)  + (this.scrollTop  || 0)
 
         // Try to match duration to the child's transform transition (default 1000ms)
         const transitionStr = childEl.style.transition || ''