Nav: Fixed an keyboard issue where holding Activate/Space for longer than two frames on a button would unnecessary keep the focus on the parent window, which could steal it from newly appearing windows. (#787)

docs/CHANGELOG.txt

@@ -63,6 +63,8 @@ Other Changes:
 - Window: Fixed using SetNextWindowPos() on a child window (which wasn't really documented) position the cursor as expected
   in the parent window, so there is no mismatch between the layout in parent and the position of the child window. 
 - InputFloat: When using ImGuiInputTextFlags_ReadOnly the step buttons are disabled. (#2257)
+- Nav: Fixed an keyboard issue where holding Activate/Space for longer than two frames on a button would unnecessary 
+  keep the focus on the parent window, which could steal it from newly appearing windows. (#787)
 - Error recovery: Extraneous/undesired calls to End() are now being caught by an assert in the End() function itself 
   at the call site (instead of being reported in EndFrame). Past the assert, they don't lead to crashes any more. (#1651)
 - Error recovery: Missing calls to End(), pass the assert, should not lead to crashes or to the fallback Debug window 

imgui.cpp

@@ -2533,6 +2533,7 @@ void ImGui::SetActiveID(ImGuiID id, ImGuiWindow* window)
     }
 }
 
+// FIXME-NAV: The existence of SetNavID/SetNavIDWithRectRel/SetFocusID is incredibly messy and confusing and needs some explanation or refactoring.
 void ImGui::SetFocusID(ImGuiID id, ImGuiWindow* window)
 {
     ImGuiContext& g = *GImGui;

imgui.h

@@ -1282,7 +1282,7 @@ struct ImGuiIO
     bool        KeySuper;                       // Keyboard modifier pressed: Cmd/Super/Windows
     bool        KeysDown[512];                  // Keyboard keys that are pressed (ideally left in the "native" order your engine has access to keyboard keys, so you can use your own defines/enums for keys).
     ImWchar     InputCharacters[16+1];          // List of characters input (translated by user from keypress+keyboard state). Fill using AddInputCharacter() helper.
-    float       NavInputs[ImGuiNavInput_COUNT]; // Gamepad inputs (keyboard keys will be auto-mapped and be written here by ImGui::NewFrame, all values will be cleared back to zero in ImGui::EndFrame)
+    float       NavInputs[ImGuiNavInput_COUNT]; // Gamepad inputs. Cleared back to zero by EndFrame(). Keyboard keys will be auto-mapped and be written here by NewFrame().
 
     // Functions
     IMGUI_API void  AddInputCharacter(ImWchar c);                       // Add new character into InputCharacters[]

imgui_widgets.cpp

@@ -488,7 +488,7 @@ bool ImGui::ButtonBehavior(const ImRect& bb, ImGuiID id, bool* out_hovered, bool
             // Set active id so it can be queried by user via IsItemActive(), equivalent of holding the mouse button.
             g.NavActivateId = id; // This is so SetActiveId assign a Nav source
             SetActiveID(id, window);
-            if (!(flags & ImGuiButtonFlags_NoNavFocus))
+            if ((nav_activated_by_code || nav_activated_by_inputs) && !(flags & ImGuiButtonFlags_NoNavFocus))
                 SetFocusID(id, window);
             g.ActiveIdAllowNavDirFlags = (1 << ImGuiDir_Left) | (1 << ImGuiDir_Right) | (1 << ImGuiDir_Up) | (1 << ImGuiDir_Down);
         }