Import Source and Translation files with text more than 1000 characters length.
Create first pair that contains at least 1000 characters in the Source text.
Create second pair.
Merge the pairs in the Source pane by Ctrl + UP.
Exit from the Edit mode (Ctrl + E).
In the Source pane select text (using Ctrl + Mouse) that starts not at beginning of the merged pair and ends in the next not aligned pair (text below the merged pair).
Fixed crash when selecting/copying text from "big blocks".