fixed.

src/gui_2.py

@@ -391,6 +391,10 @@ class App:
     # The menu bar naturally constrains the hit box height anyway.
     imgui.invisible_button("##drag_area", (drag_w, 20.0))
     if imgui.is_item_active() and imgui.is_mouse_dragging(0):
+     # CRITICAL: We must reset ImGui's mouse_down state BEFORE passing control to Windows.
+     # Otherwise, the Windows modal drag loop swallows the WM_LBUTTONUP event, 
+     # and ImGui thinks the mouse is permanently held down, causing "sticky" dragging.
+     imgui.get_io().mouse_down[0] = False
      win32gui.ReleaseCapture()
      win32gui.SendMessage(hwnd, win32con.WM_NCLBUTTONDOWN, win32con.HTCAPTION, 0)