SetItemDefaultFocus() use ScrollToRectEx(), don't tab when Alt is held either, TabItemEx() uses ItemAdd's extra_flags, misc comments.

docs/TODO.txt

@@ -326,6 +326,7 @@ It's mostly a bunch of personal notes, probably incomplete. Feel free to query i
  - nav: some features such as PageUp/Down/Home/End should probably work without ImGuiConfigFlags_NavEnableKeyboard? (where do we draw the line?)
  - nav: configuration flag to disable global shortcuts (currently only CTRL-Tab) ?
  ! nav: never clear NavId on some setup (e.g. gamepad centric)
+ - nav: scroll up/down if possible when move request fails
  - nav: there's currently no way to completely clear focus with the keyboard. depending on patterns used by the application to dispatch inputs, it may be desirable.
  - nav: code to focus child-window on restoring NavId appears to have issue: e.g. when focus change is implicit because of window closure.
  - nav: Home/End behavior when navigable item is not fully visible at the edge of scrolling? should be backtrack to keep item into view?
@@ -353,8 +354,6 @@ It's mostly a bunch of personal notes, probably incomplete. Feel free to query i
  - nav/windowing: when CTRL-Tab/windowing is active, the HoveredWindow detection doesn't take account of the window display re-ordering.
  - nav/windowing: Resizing window will currently fail with certain types of resizing constraints/callback applied
  - focus: preserve ActiveId/focus stack state, e.g. when opening a menu and close it, previously selected InputText() focus gets restored (#622)
- - focus: SetKeyboardFocusHere() on with >= 0 offset could be done on same frame (else latch and modulate on beginning of next frame)
- - focus: unable to use SetKeyboardFocusHere() on clipped widgets. (#787, #343)
 
  - inputs: we need an explicit flag about whether the imgui window is focused, to be able to distinguish focused key releases vs alt-tabbing all release behaviors.
  - inputs: rework IO system to be able to pass actual ordered/timestamped events. use an event queue? (~#335, #71)

imgui.cpp

@@ -3829,7 +3829,10 @@ void ImGui::UpdateTabFocus()
     ImGuiContext& g = *GImGui;
 
     // Pressing TAB activate widget focus
-    g.TabFocusPressed = (g.NavWindow && g.NavWindow->Active && !(g.NavWindow->Flags & ImGuiWindowFlags_NoNavInputs) && !g.IO.KeyCtrl && IsKeyPressedMap(ImGuiKey_Tab) && !IsActiveIdUsingKey(ImGuiKey_Tab));
+    g.TabFocusPressed = false;
+    if (g.NavWindow && g.NavWindow->Active && !(g.NavWindow->Flags & ImGuiWindowFlags_NoNavInputs))
+        if (!g.IO.KeyCtrl && !g.IO.KeyAlt && IsKeyPressedMap(ImGuiKey_Tab) && !IsActiveIdUsingKey(ImGuiKey_Tab))
+            g.TabFocusPressed = true;
     if (g.ActiveId == 0 && g.TabFocusPressed)
     {
         // - This path is only taken when no widget are active/tabbed-into yet.
@@ -7091,15 +7094,17 @@ void ImGui::SetItemDefaultFocus()
     ImGuiWindow* window = g.CurrentWindow;
     if (!window->Appearing)
         return;
-    if (g.NavWindow == window->RootWindowForNav && (g.NavInitRequest || g.NavInitResultId != 0) && g.NavLayer == window->DC.NavLayerCurrent)
+    if (g.NavWindow != window->RootWindowForNav || (!g.NavInitRequest && g.NavInitResultId == 0) || g.NavLayer != window->DC.NavLayerCurrent)
-    {
+        return;
+
     g.NavInitRequest = false;
     g.NavInitResultId = g.LastItemData.ID;
     g.NavInitResultRectRel = ImRect(g.LastItemData.Rect.Min - window->Pos, g.LastItemData.Rect.Max - window->Pos);
     NavUpdateAnyRequestFlag();
+
+    // Scroll could be done in NavInitRequestApplyResult() via a opt-in flag (we however don't want regular init requests to scroll)
     if (!IsItemVisible())
-            SetScrollHereY();
+        ScrollToRectEx(window, g.LastItemData.Rect, ImGuiScrollFlags_None);
-    }
 }
 
 void ImGui::SetStateStorage(ImGuiStorage* tree)
@@ -9323,7 +9328,7 @@ static void ImGui::NavUpdate()
     }
     g.NavIdIsAlive = false;
     g.NavJustTabbedId = 0;
-    IM_ASSERT(g.NavLayer == 0 || g.NavLayer == 1);
+    IM_ASSERT(g.NavLayer == ImGuiNavLayer_Main || g.NavLayer == ImGuiNavLayer_Menu);
 
     // Store our return window (for returning from Menu Layer to Main Layer) and clear it as soon as we step back in our own Layer 0
     if (g.NavWindow)

imgui_internal.h

@@ -744,7 +744,7 @@ enum ImGuiItemFlags_
     ImGuiItemFlags_SelectableDontClosePopup = 1 << 5,  // false     // Disable MenuItem/Selectable() automatically closing their popup window
     ImGuiItemFlags_MixedValue               = 1 << 6,  // false     // [BETA] Represent a mixed/indeterminate value, generally multi-selection where values differ. Currently only supported by Checkbox() (later should support all sorts of widgets)
     ImGuiItemFlags_ReadOnly                 = 1 << 7,  // false     // [ALPHA] Allow hovering interactions but underlying value is not changed.
-    ImGuiItemFlags_Inputable                = 1 << 8   // false     // [WIP] Auto-activate item when focused. Currently only used and supported by a few items before it becomes a generic feature.
+    ImGuiItemFlags_Inputable                = 1 << 8   // false     // [WIP] Auto-activate input mode when tab focused. Currently only used and supported by a few items before it becomes a generic feature.
 };
 
 // Storage for LastItem data

imgui_widgets.cpp

@@ -7879,9 +7879,7 @@ bool    ImGui::TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open,
     IMGUI_TEST_ENGINE_ITEM_INFO(id, label, g.LastItemData.StatusFlags);
     if (p_open && !*p_open)
     {
-        PushItemFlag(ImGuiItemFlags_NoNav | ImGuiItemFlags_NoNavDefaultFocus, true);
+        ItemAdd(ImRect(), id, NULL, ImGuiItemFlags_NoNav | ImGuiItemFlags_NoNavDefaultFocus);
-        ItemAdd(ImRect(), id);
-        PopItemFlag();
         return false;
     }
 
@@ -7948,9 +7946,7 @@ bool    ImGui::TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open,
     // and then gets submitted again, the tabs will have 'tab_appearing=true' but 'tab_is_new=false'.
     if (tab_appearing && (!tab_bar_appearing || tab_is_new))
     {
-        PushItemFlag(ImGuiItemFlags_NoNav | ImGuiItemFlags_NoNavDefaultFocus, true);
+        ItemAdd(ImRect(), id, NULL, ImGuiItemFlags_NoNav | ImGuiItemFlags_NoNavDefaultFocus);
-        ItemAdd(ImRect(), id);
-        PopItemFlag();
         if (is_tab_button)
             return false;
         return tab_contents_visible;