Add ability to test arbitrary rectangle for visibility without need of moving cursor.

imgui.cpp

@@ -9102,6 +9102,12 @@ bool ImGui::IsRectVisible(const ImVec2& size)
     return window->ClipRect.Overlaps(ImRect(window->DC.CursorPos, window->DC.CursorPos + size));
 }
 
+bool ImGui::IsRectVisible(const ImVec2& a, const ImVec2& b)
+{
+    ImGuiWindow* window = GetCurrentWindowRead();
+    return window->ClipRect.Overlaps(ImRect(a, b));
+}
+
 // Lock horizontal starting position + capture group bounding box into one "item" (so you can use IsItemHovered() or layout primitives such as SameLine() on whole group, etc.)
 void ImGui::BeginGroup()
 {