Manually select multiple panes to broadcast into

A clear and concise description of what you want to happen.
the exiting broadcating feature will send command to all windows on a same tab. i want half of my windows be one broadcast group and half of other in second or third broadcast windows but in same tab. in attached image i create a tab with 4 window. i want to broadcast command to G1 and G2 red-box only and then broadcast command to G1 and G2 in green-box but both be on same tab

Start by reviewing the existing broadcasting feature for how it selects windows within a tab, using the described four-window layout and screenshot as the expected scenario. Done means users can select separate pane groups in one tab and broadcast commands to each selected group independently.

Written by the indexing model from the issue text.