Contextual Menus are an important part of the Omnisphere interface, and provide convenient access to many important functions.
Right/Control-clicking almost anywhere in the Omnisphere interface will bring up a contextual menu. The contents of the menu will depend on where the cursor is placed when the contextual menu is opened.
For example, Right/Control-clicking over a blank area of the Omnisphere Header will reveal the Utility Menu. Right/Control-clicking a knob or slider will typically reveal a menu of MIDI Learn, Modulation & Automation options.