> I noticed that causing this assertion to fail is not very easy. For > example, if I drag the terminal emulator window one line at a time, I > can never cause it, even if I get to frame sizes that are much smaller > than the minimum we need for 2 windows. Somehow, I need to drag the > frame so it resizes by several lines and/or columns. Not sure why. >
I can cause the build_frame_matrix_from_leaf_window failed assertion ( glyph_row_slice_p(window_row, frame_row) is false ) when slowly resizing row by row (7→6→5 rows). The number of columns doesn't matter (can be a normal one). You can also try maximizing/unmaximizing“the window if you window manager supports it. That's a way of suddenly changing the number of rows from a normal value (e.g. 20) to a dangerous value (e.g. 4). After unmaximizing it immediately crashes (if you did the C-x 2 split).
