diff --git a/src/slic3r/GUI/CAD/DesignCanvas.cpp b/src/slic3r/GUI/CAD/DesignCanvas.cpp
index 40ac171264..7dd2b90875 100644
--- a/src/slic3r/GUI/CAD/DesignCanvas.cpp
+++ b/src/slic3r/GUI/CAD/DesignCanvas.cpp
@@ -93,6 +93,17 @@ DesignCanvas::DesignCanvas(wxWindow* parent)
     // re-entrancy guard giving up looks like. Refresh() posts a paint event instead: the current
     // frame finishes, the event loop runs (which is where ImGui's queued characters are consumed),
     // and the next frame starts clean.
+    // MEASUREMENT: does a typed character reach the GL canvas at all? Everything downstream of
+    // this point is known good (ImGui reports want_text=1 and our InputText active), so if these
+    // lines do not appear the character never got past the panel's CHAR_HOOK / the focus chain,
+    // and no amount of work inside the field will help. Skips always: a pure observer.
+    if (m_canvas_widget != nullptr && std::getenv("SNAPORCA_UXTRACE")) {
+        m_canvas_widget->Bind(wxEVT_CHAR, [](wxKeyEvent& e) {
+            fprintf(stderr, "[UX] canvas_char key=%d\n", e.GetKeyCode());
+            fflush(stderr);
+            e.Skip();
+        });
+    }
     m_inline_editor->request_frame = [this] {
         // BOTH halves, and the dirty flag first: GLCanvas3D's paint handler returns without
         // rendering when the canvas is not marked dirty, so a bare Refresh() posts an event that
diff --git a/src/slic3r/GUI/CAD/DesignPanel.cpp b/src/slic3r/GUI/CAD/DesignPanel.cpp
index 4d767ddd5e..a84d370ea0 100644
--- a/src/slic3r/GUI/CAD/DesignPanel.cpp
+++ b/src/slic3r/GUI/CAD/DesignPanel.cpp
@@ -4184,7 +4184,14 @@ DesignPanel::DesignPanel(wxWindow* parent)
             fprintf(stderr, "[KEYTRACE] key=%d ui_mode=%d is_sketching=%d in_text=%d inline_busy=%d focus=%s\n",
                     key, int(m_ui_mode), (m_viewport && m_viewport->is_sketching()) ? 1 : 0, in_text ? 1 : 0,
                     (m_viewport && m_viewport->inline_busy()) ? 1 : 0,
-                    fw ? (const char*) fw->GetClassInfo()->GetClassName() : "(none)");
+                    // wxString, not a cast: GetClassName() returns const wxChar* — wchar_t* in
+                    // this build — and casting THAT to const char* and printing it with %s emits
+                    // the first byte and stops at the padding NUL. Every focus= field this tracer
+                    // has ever printed was a single letter: "wxGLCanvas" came out as "w", and so
+                    // did "wxWindow". An instrument that silently truncates its most important
+                    // field is worse than no instrument, and this one was trusted for a whole
+                    // day's diagnosis.
+                    fw ? wxString(fw->GetClassInfo()->GetClassName()).utf8_str().data() : "(none)");
             fflush(stderr);
         }