IO: Fixed AddFocusEvent(false) to also clear MouseDown[] state. (#4921)

docs/CHANGELOG.txt

@@ -142,6 +142,7 @@ Other Changes:
 - IO: Added ImGuiKey_MouseXXX aliases for mouse buttons/wheel so all operations done on ImGuiKey
   can apply to mouse data as well. (#4921)
 - IO: Filter duplicate input events during the AddXXX() calls. (#5599, #4921)
+- IO: Fixed AddFocusEvent(false) to also clear MouseDown[] state. (#4921)
 - Menus: Fixed incorrect sub-menu parent association when opening a menu by closing another.
   Among other things, it would accidentally break part of the closing heuristic logic when moving
   towards a sub-menu. (#2517, #5614). [@rokups]

imgui.cpp

@@ -1303,6 +1303,9 @@ void ImGuiIO::ClearInputKeys()
     }
     KeyCtrl = KeyShift = KeyAlt = KeySuper = false;
     KeyMods = ImGuiMod_None;
+    MousePos = ImVec2(-FLT_MAX, -FLT_MAX);
+    memset(MouseDown, 0, sizeof(MouseDown));
+    MouseWheel = MouseWheelH = 0.0f;
 }
 
 static ImGuiInputEvent* FindLatestInputEvent(ImGuiInputEventType type, int arg = -1)