I've seen several posts on this issue, but none of the solutions presented are working. This issue has been plaguing me for a while now. At this time I'm using webstorm v2018.3. When I recently started a new project the terminal is docked, but for my primary project it will not dock with the following solutions.
1) With the terminal in windowed mode, if I deselect windowed mode from the termainal it goes to floating mode.
2) In the menu Window > Active Tool Window the option to go to docked mode is greyed out. If I deselect windowed mode from this menu it goes to floating mode, and docked mode is still greyed out.
If anyone has a solution, I'm all ears, this is extremely frustrating.