3.4 Crashes in Windows in the following situation :
Begin a render with that has multiple populations that normally take two or three minutes to populate.
Without waiting for the population progress window to finish Close out the preview window
Immediately Minimize the Terragen window
Immediately Minimize the Render window
The small population windows continue to pop up on the screen with the percentage of completion. Then there is a crash, seemingly upon the last population popup completing.
I only found this out when intending to leave the house and have the render running for several hours and wanting to have the computer screen not updating while the render proceeded.
Leaving all Terragen widows up on screen until the populations are done lets the render complete normally.