Nav, Internals: wrap changes to g.NavWindow into a helper function to help track/log changes.

Amend 076d8fc. Eventually we should REALLY clean up the SetNavWindow SetNavID SetFocusID FocusWindow fiasco.

docs/TODO.txt

@@ -113,6 +113,8 @@ It's mostly a bunch of personal notes, probably incomplete. Feel free to query i
  - layout: (R&D) local multi-pass layout mode.
  - layout: (R&D) bind authored layout data (created by an off-line tool), items fetch their pos/size at submission, self-optimize data structures to stable linear access.
 
+ - tables: see https://github.com/ocornut/imgui/issues/2957#issuecomment-569726095
+
  - group: BeginGroup() needs a border option. (~#1496)
  - group: IsHovered() after EndGroup() covers whole AABB rather than the intersection of individual items. Is that desirable?
  - group: merge deactivation/activation within same group (fwd WasEdited flag). (#2550)

imgui.cpp

@@ -6784,16 +6784,13 @@ void ImGui::FocusWindow(ImGuiWindow* window)
 
     if (g.NavWindow != window)
     {
-        IMGUI_DEBUG_LOG_FOCUS("[focus] FocusWindow(\"%s\")\n", window ? window->Name : "<NULL>");
+        SetNavWindow(window);
-        g.NavWindow = window;
         if (window && g.NavDisableMouseHover)
             g.NavMousePosDirty = true;
         g.NavId = window ? window->NavLastIds[0] : 0; // Restore NavId
+        g.NavLayer = ImGuiNavLayer_Main;
         g.NavFocusScopeId = 0;
         g.NavIdIsAlive = false;
-        g.NavLayer = ImGuiNavLayer_Main;
-        g.NavInitRequest = g.NavMoveSubmitted = g.NavMoveScoringItems = false;
-        NavUpdateAnyRequestFlag();
     }
 
     // Close popups if any
@@ -7387,8 +7384,7 @@ void ImGui::SetKeyboardFocusHere(int offset)
     ImGuiWindow* window = g.CurrentWindow;
     IM_ASSERT(offset >= -1);    // -1 is allowed but not below
 
-    g.NavWindow = window;
+    SetNavWindow(window);
-    g.NavInitRequest = g.NavMoveSubmitted = g.NavMoveScoringItems = false;
 
     ImGuiScrollFlags scroll_flags = window->Appearing ? ImGuiScrollFlags_KeepVisibleEdgeX | ImGuiScrollFlags_AlwaysCenterY : ImGuiScrollFlags_KeepVisibleEdgeX | ImGuiScrollFlags_KeepVisibleEdgeY;
     NavMoveRequestSubmit(ImGuiDir_None, offset < 0 ? ImGuiDir_Up : ImGuiDir_Down, ImGuiNavMoveFlags_Tabbing | ImGuiNavMoveFlags_FocusApi, scroll_flags); // FIXME-NAV: Once we refactor tabbing, add LegacyApi flag to not activate non-inputable.
@@ -9561,8 +9557,22 @@ ImVec2 ImGui::FindBestWindowPosForPopup(ImGuiWindow* window)
 // [SECTION] KEYBOARD/GAMEPAD NAVIGATION
 //-----------------------------------------------------------------------------
 
-// FIXME-NAV: The existence of SetNavID vs SetFocusID properly needs to be clarified/reworked.
+// FIXME-NAV: The existence of SetNavID vs SetFocusID vs FocusWindow() needs to be clarified/reworked.
-// In our terminology those should be interchangeable. Those two functions are merely a legacy artifact, so at minimum naming should be clarified.
+// In our terminology those should be interchangeable, yet right now this is super confusing.
+// Those two functions are merely a legacy artifact, so at minimum naming should be clarified.
+
+void ImGui::SetNavWindow(ImGuiWindow* window)
+{
+    ImGuiContext& g = *GImGui;
+    if (g.NavWindow != window)
+    {
+        IMGUI_DEBUG_LOG_FOCUS("[focus] SetNavWindow(\"%s\")\n", window ? window->Name : "<NULL>");
+        g.NavWindow = window;
+    }
+    g.NavInitRequest = g.NavMoveSubmitted = g.NavMoveScoringItems = false;
+    NavUpdateAnyRequestFlag();
+}
+
 void ImGui::SetNavID(ImGuiID id, ImGuiNavLayer nav_layer, ImGuiID focus_scope_id, const ImRect& rect_rel)
 {
     ImGuiContext& g = *GImGui;
@@ -9580,15 +9590,12 @@ void ImGui::SetFocusID(ImGuiID id, ImGuiWindow* window)
     ImGuiContext& g = *GImGui;
     IM_ASSERT(id != 0);
 
+    if (g.NavWindow != window)
+       SetNavWindow(window);
+
     // Assume that SetFocusID() is called in the context where its window->DC.NavLayerCurrent and window->DC.NavFocusScopeIdCurrent are valid.
     // Note that window may be != g.CurrentWindow (e.g. SetFocusID call in InputTextEx for multi-line text)
     const ImGuiNavLayer nav_layer = window->DC.NavLayerCurrent;
-    if (g.NavWindow != window)
-    {
-        g.NavWindow = window;
-        g.NavInitRequest = g.NavMoveSubmitted = g.NavMoveScoringItems = false;
-        NavUpdateAnyRequestFlag();
-    }
     g.NavId = id;
     g.NavLayer = nav_layer;
     g.NavFocusScopeId = window->DC.NavFocusScopeIdCurrent;
@@ -9837,11 +9844,7 @@ static void ImGui::NavProcessItem()
     if (g.NavId == id)
     {
         if (g.NavWindow != window)
-        {
+            SetNavWindow(window); // Always refresh g.NavWindow, because some operations such as FocusItem() may not have a window.
-            g.NavWindow = window;                                           // Always refresh g.NavWindow, because some operations such as FocusItem() don't have a window.
-            g.NavInitRequest = g.NavMoveSubmitted = g.NavMoveScoringItems = false;
-            NavUpdateAnyRequestFlag();
-        }
         g.NavLayer = window->DC.NavLayerCurrent;
         g.NavFocusScopeId = window->DC.NavFocusScopeIdCurrent;
         g.NavIdIsAlive = true;
@@ -9990,7 +9993,12 @@ void ImGui::NavRestoreLayer(ImGuiNavLayer layer)
 {
     ImGuiContext& g = *GImGui;
     if (layer == ImGuiNavLayer_Main)
+    {
+        ImGuiWindow* prev_nav_window = g.NavWindow;
         g.NavWindow = NavRestoreLastChildNavWindow(g.NavWindow);    // FIXME-NAV: Should clear ongoing nav requests?
+        if (prev_nav_window)
+            IMGUI_DEBUG_LOG_FOCUS("[focus] NavRestoreLayer: from \"%s\" to SetNavWindow(\"%s\")\n", prev_nav_window->Name, g.NavWindow->Name);
+    }
     ImGuiWindow* window = g.NavWindow;
     if (window->NavLastIds[layer] != 0)
     {
@@ -10527,7 +10535,11 @@ void ImGui::NavMoveRequestApplyResult()
         }
     }
 
-    g.NavWindow = result->Window;
+    if (g.NavWindow != result->Window)
+    {
+        IMGUI_DEBUG_LOG_FOCUS("[focus] NavMoveRequest: SetNavWindow(\"%s\")\n", result->Window->Name);
+        g.NavWindow = result->Window;
+    }
     if (g.ActiveId != result->ID)
         ClearActiveID();
     if (g.NavId != result->ID)

imgui_internal.h

@@ -2671,6 +2671,7 @@ namespace ImGui
     IMGUI_API ImVec2        GetNavInputAmount2d(ImGuiNavDirSourceFlags dir_sources, ImGuiNavReadMode mode, float slow_factor = 0.0f, float fast_factor = 0.0f);
     IMGUI_API int           CalcTypematicRepeatAmount(float t0, float t1, float repeat_delay, float repeat_rate);
     IMGUI_API void          ActivateItem(ImGuiID id);   // Remotely activate a button, checkbox, tree node etc. given its unique ID. activation is queued and processed on the next frame when the item is encountered again.
+    IMGUI_API void          SetNavWindow(ImGuiWindow* window);
     IMGUI_API void          SetNavID(ImGuiID id, ImGuiNavLayer nav_layer, ImGuiID focus_scope_id, const ImRect& rect_rel);
 
     // Focus Scope (WIP)