how to write text into Gmail Message Body by other browser

[umibe hosizora]

I would like to do the following:

1. Open a web page → login gmail → compose mail
2. Open other web page →　Select a bookmark, open a java webapp(worked in tomcat)
3. The webapp will copy some text into the above Gmail's Message Body

●bookmark uses bookmarklet(javascript).

[umibe hosizora]

if the two pages are different tabs in same browser , is it possible?

[Rob Spoor]

Proper browsers disallow this, as this behaviour (called cross-site scripting, or XSS) offers a great potential for hacking sites.