In the Online E-learning .fmb module, data block items are displayed on two content canvases. A set of icon buttons is defined that users must have access to at all times. Which canvases type is appropriate to display the buttons?

For icon buttons that must always be accessible while users work with content canvases, a Horizontal Toolbar canvas associated with the same window is the appropriate choice. Toolbar canvases are specifically designed to display buttons or iconic items that remain visible and accessible regardless of navigation within content canvases. Options A and B are incorrect because overlay canvases are for conditional display, not persistent access. Option C is incorrect because a second content canvas doesn't provide button persistence. Option D is incorrect because a separate window would hide buttons when the main window is active.