Add context menu based on multiple selection of project items across solution using visual studio addin

I have been working on visual studio Add-in for quiet some time.

I need to add context menu for project item. This can done as follows.

CommandBar vsBarItem = cmdBars["Item"];//the pop up for clicking a project Item

This context menu is visible only on the single/multiple selection of project items inside a single project selection.

Is there a way to add context menu for selection of multiple project items inside the solution ( irrespective of the project being selected). To be more precise, for ex

I have 2 projects in solution namely Project A and project B. If Project A contains projectItem1, ProjectItem2 and If Project B contains projectItem3, projectItem4.

I need a context menu when I select ProjectItem1 and ProjectItem4.

References:

I tried all the below options but in vain :(

CommandBar vsBarMultipleSelection = cmdBars["Multi-Select"];CommandBar vsBarMultipleSelection = cmdBars["Multiple selections"];

Please let me know which item of commandBar API should I use, so that I will have context menu for multiple selection.

Thanks in Advance,

Best Regards, Shishi