Summary

This PR adds a new keyword Drag And Drop To Frame that reliably supports dragging an element from the main document into a target element inside an iframe.

Motivation

While automating post-deployment tasks in a Salesforce Service Cloud setup flow, I encountered a limitation where drag-and-drop interactions failed when the drop target resided inside an iframe. The existing keywords could not handle this scenario because the WebDriver action chain loses context when switching into an iframe mid-action.

Real-world scenario: Salesforce Service Cloud application

• Login → Setup → All Sites → Builder → Select Dashboard → Drag and drop a component into the target section (inside an iframe) → Publish → Confirm publish.
• The existing Drag And Drop keywords failed because the target is inside an iframe.

This limitation aligns with

• long-standing issue Drag and drop across iframe bounds is problematic #120 (cross-frame drag-and-drop limitation)
• related discussion in Relative Locators, iFrames, ShadowDom, RTL .. oh my! #1813 around iframe handling

By introducing this keyword, the drag-and-drop flow can now be reliably automated end-to-end.

Changes:

• Added implementation in src/SeleniumLibrary/keywords/element.py
• Added acceptance tests in atest/acceptance/keywords/draganddropframe.robot
• Added test HTML page atest/resources/html/frames/draganddrop.html
• Updated unit test keyword count in utest/test/api/test_plugins.py

All acceptance tests pass locally, including the new cross-frame scenarios.

All acceptance tests pass locally (including new ones).

This is a non-trivial enhancement — please add the acknowledge label to #120 for release notes credit. Thank you!