Tables: Fixed an issue where user's Y cursor movement within a hidden column would have side-effects.

- Afaik the "to allow ImGuiListClipper to function" was added early during Tables development (prior to commit 55) and later replaced by support in ImGuiListCipper, it seems unnecessary.
- Also removed RowPosY2 being accted in TableEndCell().
+ Comments about 2bb9e35 + fix example bb224c8

examples/example_emscripten_wgpu/main.cpp

@@ -127,6 +127,8 @@ static bool InitWGPU()
 
 static void MainLoopStep(void* window)
 {
+    ImGuiIO& io = ImGui::GetIO();
+
     glfwPollEvents();
 
     int width, height;