From fb44f5347fec6950463a8e13671fbe1ff891fde5 Mon Sep 17 00:00:00 2001
From: joranv1 <joran.vancoillie@gmail.com>
Date: Mon, 31 Aug 2026 15:51:42 +0200
Subject: [PATCH] FIX: filament vendor submenu never opens when each group has
 one preset

Hovering a category row (Custom, Bambu, Generic, ...) in the Project
Filaments dropdown is supposed to open a submenu listing that vendor's
presets. Often it does nothing at all.

DropDown::hoverIndex() short-circuits on `count == items.size()` and
returns the row index unchanged, assuming equal counts mean nothing is
grouped. That does not hold when every group contains exactly one item:
each group still collapses to a single row, so the counts match while
grouping is present. The -i-2 group-row encoding is then never produced
and mouseMove() cannot open the submenu.

This is why it looks intermittent. It depends only on the preset list --
as soon as one vendor has two or more compatible presets the counts
differ, the shortcut is skipped, and every submenu works again.

Track has_groups in messureSize() next to count and require it to be
false before taking the shortcut. selectedItem() had the same flaw,
mispositioning the check mark in the affected lists. Also guard the
subDropDown dereference in mouseMove(), which this makes reachable.
---
 src/slic3r/GUI/Widgets/DropDown.cpp | 8 +++++---
 src/slic3r/GUI/Widgets/DropDown.hpp | 1 +
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/slic3r/GUI/Widgets/DropDown.cpp b/src/slic3r/GUI/Widgets/DropDown.cpp
index d905b8a8eaf..8f1d30b6b53 100644
--- a/src/slic3r/GUI/Widgets/DropDown.cpp
+++ b/src/slic3r/GUI/Widgets/DropDown.cpp
@@ -418,7 +418,8 @@ int DropDown::hoverIndex()
 {
     if (hover_item < 0)
         return -1;
-    if (count == items.size())
+    // Counts also match when every group holds one item, so check has_groups too
+    if (count == items.size() && !has_groups)
         return hover_item;
     int index = -1;
     std::set<wxString> groups;
@@ -446,7 +447,7 @@ int DropDown::selectedItem()
 {
     if (selection < 0)
         return -1;
-    if (count == items.size())
+    if (count == items.size() && !has_groups)
         return selection;
     auto & sel = items[selection];
     if (group.IsEmpty() ? !sel.group.IsEmpty() : sel.group != group)
@@ -559,6 +560,7 @@ void DropDown::messureSize()
     // Gtk has a wrapper window for popup widget
     gtk_window_resize (GTK_WINDOW (m_widget), szContent.x, szContent.y);
 #endif
+    has_groups = !groups.empty();
     if (!groups.empty() && subDropDown == nullptr) {
         subDropDown = new DropDown(items);
         subDropDown->mainDropDown = this;
@@ -715,7 +717,7 @@ void DropDown::mouseMove(wxMouseEvent &event)
         if (hover == hover_item) return;
         hover_item = hover;
         int index  = hoverIndex();
-        if (index < -1) {
+        if (index < -1 && subDropDown) {
             auto & drop = *subDropDown;
             drop.group  = items[-index - 2].group;
             drop.need_sync = true;
diff --git a/src/slic3r/GUI/Widgets/DropDown.hpp b/src/slic3r/GUI/Widgets/DropDown.hpp
index ac3ea717211..10da61d7e20 100644
--- a/src/slic3r/GUI/Widgets/DropDown.hpp
+++ b/src/slic3r/GUI/Widgets/DropDown.hpp
@@ -37,6 +37,7 @@ class DropDown : public PopupWindow
 private:
     std::vector<Item> &items;
     size_t             count = 0;
+    bool               has_groups = false; // set by messureSize()
     wxString           group;
     bool               need_sync  = false;
     int                selection  = -1;