Organizer: preserve sibling expand state across tree refresh (#1)

Root-caused a 2013 bug report (verahill.blogspot.com, "creating a new
directory causes all open directories lower in rank to auto-close") that
turned out to still be live: CalcMgr::createResource() calls
p_treeCtrl->refresh(parent), where parent defaults to whatever's
currently selected -- typically the shared parent directory you
right-click to create a new child under, not the new child itself.
refresh() -> loadChildren(node, true) does a full delete-and-rebuild of
*every* direct child of that parent, and freshly-rebuilt tree items
default to collapsed -- so any sibling directory you had open elsewhere
under the same parent silently collapses too, even though nothing about
it actually changed.

Fixed by having refresh() record which children are expanded before the
delete-and-rebuild (keyed by resource URL, since the old wxTreeItemIds
don't survive the rebuild), then re-expanding the matching freshly-built
children afterward. Re-expanding a freshly-built (currently childless)
item triggers the normal wxEVT_TREE_ITEM_EXPANDING handler
(CalcMgr::OnTreectrlItemExpanding), which lazily reloads that child's own
children exactly as if the user had expanded it by hand -- so the whole
previously-expanded branch comes back, not just the top-level node.

This is refresh()'s own general mechanism, not a createResource()-special
case -- fixes the same collapse side effect for all ~13 other call sites
(rename, move, drag-drop, ...), not just resource creation.

Verified via a full local build (organizer links clean); not yet
re-tested live against the exact two-open-directories repro from the
original report.

Author: andy

src/wxgui/wxtools/WxResourceTreeCtrl.C

@@ -37,6 +37,8 @@
 
 #include <iostream>
 using std::cerr;
+#include <set>
+using std::set;
 using std::endl;
 
 #include "wx/treectrl.h"
@@ -607,6 +609,35 @@ void WxResourceTreeCtrl::refresh(WxResourceTreeItemData * node)
   }
 
   if (setExpandable(node)) {
+    // loadChildren(node, true) deletes and rebuilds *every* direct child of
+    // node, not just the one that actually changed -- freshly-rebuilt items
+    // default to collapsed, so any sibling the user had expanded (e.g. a
+    // second job directory open alongside the one they're actually working
+    // in) silently collapses too. Recording which children were expanded
+    // beforehand and re-expanding their same-URL replacements afterward
+    // fixes this without changing refresh()'s actual reload semantics --
+    // GitHub #1, reported originally in 2013 ("creating a new directory
+    // causes all open directories lower in rank to auto-close"), still
+    // reproducible via the exact mechanism this fixes: CalcMgr::
+    // createResource() calls refresh(parent), and parent is whatever's
+    // currently selected -- typically the shared parent directory you
+    // right-clicked to create the new child under, not just the new child
+    // itself.
+    std::set<string> expandedUrls;
+    {
+      wxTreeItemId nodeId = node->GetId();
+      wxTreeItemIdValue cookie;
+      wxTreeItemId childId = GetFirstChild(nodeId, cookie);
+      for (; childId.IsOk(); childId = GetNextChild(nodeId, cookie)) {
+        if (IsExpanded(childId)) {
+          WxResourceTreeItemData * child =
+            dynamic_cast<WxResourceTreeItemData *>(GetItemData(childId));
+          if (child && child->getResource())
+            expandedUrls.insert(child->getResource()->getURL().toString());
+        }
+      }
+    }
+
     loadChildren(node, true);
     wxTreeItemId nodeId = node->GetId();
     wxTreeItemIdValue cookie;
@@ -616,6 +647,11 @@ void WxResourceTreeCtrl::refresh(WxResourceTreeItemData * node)
         dynamic_cast<WxResourceTreeItemData *>(GetItemData(childId));
       child->getResource()->clearChildren();
       DeleteChildren(childId);
+      // Re-expanding triggers the normal wxEVT_TREE_ITEM_EXPANDING handler
+      // (CalcMgr::OnTreectrlItemExpanding), which lazily loads this child's
+      // own children exactly as if the user had expanded it themselves.
+      if (expandedUrls.count(child->getResource()->getURL().toString()))
+        Expand(childId);
     }
   }