diff --git a/3rdparty/dear-imgui/imgui.cpp b/3rdparty/dear-imgui/imgui.cpp
index 143197562..7fb0508c7 100644
--- a/3rdparty/dear-imgui/imgui.cpp
+++ b/3rdparty/dear-imgui/imgui.cpp
@@ -672,8 +672,8 @@ CODE
      you to animate labels. For example you may want to include varying information in a window title bar,
      but windows are uniquely identified by their ID. Use "###" to pass a label that isn't part of ID:
 
-       Button("Hello###ID";   // Label = "Hello",  ID = hash of (..., "ID")
-       Button("World###ID";   // Label = "World",  ID = hash of (..., "ID")     // Same as above, even though the label looks different
+       Button("Hello###ID");  // Label = "Hello",  ID = hash of (..., "ID")
+       Button("World###ID");  // Label = "World",  ID = hash of (..., "ID")     // Same as above, even though the label looks different
 
        sprintf(buf, "My game (%f FPS)###MyGame", fps);
        Begin(buf);            // Variable title,   ID = hash of "MyGame"
@@ -3303,8 +3303,9 @@ void ImGui::NewFrame()
     g.CurrentPopupStack.resize(0);
     ClosePopupsOverWindow(g.NavWindow);
 
-    // Create implicit window - we will only render it if the user has added something to it.
+    // Create implicit/fallback window - which we will only render it if the user has added something to it.
     // We don't use "Debug" to avoid colliding with user trying to create a "Debug" window with custom flags.
+    // This fallback is particularly important as it avoid ImGui:: calls from crashing.
     SetNextWindowSize(ImVec2(400,400), ImGuiCond_FirstUseEver);
     Begin("Debug##Default");
 
@@ -4459,7 +4460,7 @@ static void ImGui::UpdateManualResize(ImGuiWindow* window, const ImVec2& size_au
     ImGuiWindowFlags flags = window->Flags;
     if ((flags & ImGuiWindowFlags_NoResize) || (flags & ImGuiWindowFlags_AlwaysAutoResize) || window->AutoFitFramesX > 0 || window->AutoFitFramesY > 0)
         return;
-    if (window->WasActive == false) // Early out to avoid running this code for e.g. an hidden implicit Debug window.
+    if (window->WasActive == false) // Early out to avoid running this code for e.g. an hidden implicit/fallback Debug window.
         return;
 
     const int resize_border_count = g.IO.ConfigResizeWindowsFromEdges ? 4 : 0;
diff --git a/3rdparty/dear-imgui/imgui.h b/3rdparty/dear-imgui/imgui.h
index ed9f4350c..5c04146f9 100644
--- a/3rdparty/dear-imgui/imgui.h
+++ b/3rdparty/dear-imgui/imgui.h
@@ -44,8 +44,8 @@ Index of this file:
 
 // Version
 // (Integer encoded as XYYZZ for use in #if preprocessor conditionals. Work in progress versions typically starts at XYY00 then bounced up to XYY01 when release tagging happens)
-#define IMGUI_VERSION               "1.67 WIP"
-#define IMGUI_VERSION_NUM           16700
+#define IMGUI_VERSION               "1.66b"
+#define IMGUI_VERSION_NUM           16602
 #define IMGUI_CHECKVERSION()        ImGui::DebugCheckVersionAndDataLayout(IMGUI_VERSION, sizeof(ImGuiIO), sizeof(ImGuiStyle), sizeof(ImVec2), sizeof(ImVec4), sizeof(ImDrawVert))
 
 // Define attributes of all API symbols declarations (e.g. for DLL under Windows)
@@ -1904,9 +1904,9 @@ struct ImFontAtlas
     // Building in RGBA32 format is provided for convenience and compatibility, but note that unless you manually manipulate or copy color data into 
     // the texture (e.g. when using the AddCustomRect*** api), then the RGB pixels emitted will always be white (~75% of memory/bandwidth waste.
     IMGUI_API bool              Build();                    // Build pixels data. This is called automatically for you by the GetTexData*** functions.
-    IMGUI_API bool              IsBuilt()                   { return Fonts.Size > 0 && (TexPixelsAlpha8 != NULL || TexPixelsRGBA32 != NULL); }
     IMGUI_API void              GetTexDataAsAlpha8(unsigned char** out_pixels, int* out_width, int* out_height, int* out_bytes_per_pixel = NULL);  // 1 byte per-pixel
     IMGUI_API void              GetTexDataAsRGBA32(unsigned char** out_pixels, int* out_width, int* out_height, int* out_bytes_per_pixel = NULL);  // 4 bytes-per-pixel
+    bool                        IsBuilt()                   { return Fonts.Size > 0 && (TexPixelsAlpha8 != NULL || TexPixelsRGBA32 != NULL); }
     void                        SetTexID(ImTextureID id)    { TexID = id; }
 
     //-------------------------------------------
diff --git a/3rdparty/dear-imgui/imgui_demo.cpp b/3rdparty/dear-imgui/imgui_demo.cpp
index b71d6262f..1571bda1c 100644
--- a/3rdparty/dear-imgui/imgui_demo.cpp
+++ b/3rdparty/dear-imgui/imgui_demo.cpp
@@ -199,7 +199,7 @@ void ImGui::ShowDemoWindow(bool* p_open)
 
     if (show_app_metrics)             { ImGui::ShowMetricsWindow(&show_app_metrics); }
     if (show_app_style_editor)        { ImGui::Begin("Style Editor", &show_app_style_editor); ImGui::ShowStyleEditor(); ImGui::End(); }
-    if (show_app_about)               { ShowAboutWindow(&show_app_about); }
+    if (show_app_about)               { ImGui::ShowAboutWindow(&show_app_about); }
 
     // Demonstrate the various window flags. Typically you would just use the default!
     static bool no_titlebar = false;
@@ -2459,7 +2459,7 @@ static void ShowDemoWindowMisc()
 void ImGui::ShowAboutWindow(bool* p_open)
 {
     ImGui::Begin("About Dear ImGui", p_open, ImGuiWindowFlags_AlwaysAutoResize);
-    ImGui::Text("Dear ImGui, %s", ImGui::GetVersion());
+    ImGui::Text("Dear ImGui %s", ImGui::GetVersion());
     ImGui::Separator();
     ImGui::Text("By Omar Cornut and all dear imgui contributors.");
     ImGui::Text("Dear ImGui is licensed under the MIT License, see LICENSE for more information.");