I will open a new message window up and start to type. There are some delays in the keystrokes registering. Then all of a sudden the new message window will minimize and the main Thunderbird program comes up. They keystrokes will start registering and I get a bunch of hotkey commands overtaking my inbox (deleting, categorizing, labeling, jumping to old messages, etc). Needless to say it really gets annoying when all of a sudden 10 different commands go to messages in my inbox. I don't know all the damage those delayed keystrokes have done if it deletes them etc. without me knowing.

Is this a Windows 10 problem? Why is the main program suddenly becoming the active window? I am usually working on several drafts of messages at once. Is it a memory issue? Is it becoming active when it is searching for new messages that have income?