Internals: adding ImGuiNavMoveFlags_NoClearActiveId even though there's currently no satisfying way to take advantage of it. (#1418)

imgui.cpp

@@ -12303,8 +12303,10 @@ void ImGui::NavMoveRequestApplyResult()
         g.NavLastValidSelectionUserData = ImGuiSelectionUserData_Invalid;
     }
 
-    // FIXME: Could become optional e.g. ImGuiNavMoveFlags_NoClearActiveId if we later want to apply navigation requests without altering active input.
+    // Clear active id unless requested not to
-    if (g.ActiveId != result->ID)
+    // FIXME: ImGuiNavMoveFlags_NoClearActiveId is currently unused as we don't have a clear strategy to preserve active id after interaction,
+    // so this is mostly provided as a gateway for further experiments (see #1418, #2890)
+    if (g.ActiveId != result->ID && (g.NavMoveFlags & ImGuiNavMoveFlags_NoClearActiveId) == 0)
         ClearActiveID();
 
     // Don't set NavJustMovedToId if just landed on the same spot (which may happen with ImGuiNavMoveFlags_AllowCurrentNavId)

imgui_internal.h

@@ -1578,6 +1578,7 @@ enum ImGuiNavMoveFlags_
     ImGuiNavMoveFlags_Activate              = 1 << 12,  // Activate/select target item.
     ImGuiNavMoveFlags_NoSelect              = 1 << 13,  // Don't trigger selection by not setting g.NavJustMovedTo
     ImGuiNavMoveFlags_NoSetNavHighlight     = 1 << 14,  // Do not alter the visible state of keyboard vs mouse nav highlight
+    ImGuiNavMoveFlags_NoClearActiveId       = 1 << 15,  // (Experimental) Do not clear active id when applying move result
 };
 
 enum ImGuiNavLayer