Re: Redisplay issue

[Yuan MEI]

> The "good" and the "bad" traces are completely identical!
>
> Can you add 2 more traces as in the diffs below, recompile, and repeat
> the experiment?  I'd like to be sure that the traces are identical
> down to the screen line level.

Bad exposure:

redisplay_preserve_echo_area (8)
redisplay_internal 0
redisplay_preserve_echo_area (9)
redisplay_internal 0
0x2d408d0 ( SPEEDBAR): same window start
0x2d408d0 ( SPEEDBAR): 1
0x13cbc30 (HELLO): same window start
0x13cbc30 (HELLO): 1
expose_frame (0, 0, 170, 1026)
expose_window (1, 1, 168, 1024)
expose_line 0: (0, 0, 168, 1024)
expose_line 16: (0, 0, 168, 1024)
expose_line 32: (0, 0, 168, 1024)
expose_line 48: (0, 0, 168, 1024)
expose_line 64: (0, 0, 168, 1024)
expose_line 80: (0, 0, 168, 1024)
expose_line 96: (0, 0, 168, 1024)
expose_line 112: (0, 0, 168, 1024)
expose_line 128: (0, 0, 168, 1024)
expose_line 144: (0, 0, 168, 1024)
expose_line 160: (0, 0, 168, 1024)
expose_line 176: (0, 0, 168, 1024)
expose_line 192: (0, 0, 168, 1024)
expose_line 208: (0, 0, 168, 1024)
expose_line 224: (0, 0, 168, 1024)
expose_line 240: (0, 0, 168, 1024)
expose_line 256: (0, 0, 168, 1024)
expose_line 272: (0, 0, 168, 1024)
expose_line 288: (0, 0, 168, 1024)
expose_line 304: (0, 0, 168, 1024)
expose_line 320: (0, 0, 168, 1024)
expose_line 336: (0, 0, 168, 1024)
expose_line 352: (0, 0, 168, 1024)
expose_line 368: (0, 0, 168, 1024)
expose_line 384: (0, 0, 168, 1024)
expose_line 400: (0, 0, 168, 1024)
expose_line 416: (0, 0, 168, 1024)
expose_line 432: (0, 0, 168, 1024)
expose_line 448: (0, 0, 168, 1024)
expose_line 464: (0, 0, 168, 1024)
expose_line 480: (0, 0, 168, 1024)
expose_line 496: (0, 0, 168, 1024)
expose_line 512: (0, 0, 168, 1024)
expose_line 528: (0, 0, 168, 1024)
expose_line 544: (0, 0, 168, 1024)
expose_line 560: (0, 0, 168, 1024)
expose_line 576: (0, 0, 168, 1024)
expose_line 592: (0, 0, 168, 1024)
expose_line 608: (0, 0, 168, 1024)
expose_line 624: (0, 0, 168, 1024)
expose_line 640: (0, 0, 168, 1024)
expose_line 656: (0, 0, 168, 1024)
expose_line 672: (0, 0, 168, 1024)
expose_line 688: (0, 0, 168, 1024)
expose_line 704: (0, 0, 168, 1024)
expose_line 720: (0, 0, 168, 1024)
expose_line 736: (0, 0, 168, 1024)
expose_line 752: (0, 0, 168, 1024)
expose_line 768: (0, 0, 168, 1024)
expose_line 784: (0, 0, 168, 1024)
expose_line 800: (0, 0, 168, 1024)
expose_line 816: (0, 0, 168, 1024)
expose_line 832: (0, 0, 168, 1024)
expose_line 848: (0, 0, 168, 1024)
expose_line 864: (0, 0, 168, 1024)
expose_line 880: (0, 0, 168, 1024)
expose_line 896: (0, 0, 168, 1024)
expose_line 912: (0, 0, 168, 1024)
expose_line 928: (0, 0, 168, 1024)
expose_line 944: (0, 0, 168, 1024)
expose_line 960: (0, 0, 168, 1024)
expose_line 976: (0, 0, 168, 1024)
expose_line 992: (0, 0, 168, 1024)
expose_line 1008: (0, 0, 168, 1024)
expose_window (1, 0, 168, 0)
expose_window (1, 0, 168, 0)
expose_frame (0, 0, 818, 1026)
expose_window (1, 17, 816, 992)
expose_line 0: (0, 0, 816, 992)
expose_line 16: (0, 0, 816, 992)
expose_line 32: (0, 0, 816, 992)
expose_line 48: (0, 0, 816, 992)
expose_line 64: (0, 0, 816, 992)
expose_line 80: (0, 0, 816, 992)
expose_line 101: (0, 0, 816, 992)
expose_line 123: (0, 0, 816, 992)
expose_line 139: (0, 0, 816, 992)
expose_line 158: (0, 0, 816, 992)
expose_line 177: (0, 0, 816, 992)
expose_line 196: (0, 0, 816, 992)
expose_line 222: (0, 0, 816, 992)
expose_line 243: (0, 0, 816, 992)
expose_line 265: (0, 0, 816, 992)
expose_line 286: (0, 0, 816, 992)
expose_line 307: (0, 0, 816, 992)
expose_line 323: (0, 0, 816, 992)
expose_line 339: (0, 0, 816, 992)
expose_line 355: (0, 0, 816, 992)
expose_line 371: (0, 0, 816, 992)
expose_line 390: (0, 0, 816, 992)
expose_line 409: (0, 0, 816, 992)
expose_line 430: (0, 0, 816, 992)
expose_line 447: (0, 0, 816, 992)
expose_line 463: (0, 0, 816, 992)
expose_line 484: (0, 0, 816, 992)
expose_line 505: (0, 0, 816, 992)
expose_line 521: (0, 0, 816, 992)
expose_line 537: (0, 0, 816, 992)
expose_line 559: (0, 0, 816, 992)
expose_line 580: (0, 0, 816, 992)
expose_line 601: (0, 0, 816, 992)
expose_line 622: (0, 0, 816, 992)
expose_line 643: (0, 0, 816, 992)
expose_line 664: (0, 0, 816, 992)
expose_line 685: (0, 0, 816, 992)
expose_line 706: (0, 0, 816, 992)
expose_line 728: (0, 0, 816, 992)
expose_line 747: (0, 0, 816, 992)
expose_line 766: (0, 0, 816, 992)
expose_line 787: (0, 0, 816, 992)
expose_line 806: (0, 0, 816, 992)
expose_line 822: (0, 0, 816, 992)
expose_line 838: (0, 0, 816, 992)
expose_line 857: (0, 0, 816, 992)
expose_line 879: (0, 0, 816, 992)
expose_line 898: (0, 0, 816, 992)
expose_line 917: (0, 0, 816, 992)
expose_line 938: (0, 0, 816, 992)
expose_line 959: (0, 0, 816, 992)
expose_line 975: (0, 0, 816, 992)
expose_line 976: (0, 0, 816, 992)
expose_window (1, 1009, 816, 16)
expose_line 0: (0, 0, 816, 16)
expose_window (1, 16, 816, 0)
expose_window (1, 0, 816, 16)
expose_line 0: (0, 0, 816, 16)
redisplay_preserve_echo_area (8)
redisplay_internal 0
0x2d408d0 ( SPEEDBAR): same window start
0x2d408d0 ( SPEEDBAR): 1
0x13cbc30 (HELLO): same window start
0x13cbc30 (HELLO): 1
redisplay_preserve_echo_area (9)
redisplay_internal 0

Good exposure:

redisplay_preserve_echo_area (8)
redisplay_internal 0
0x2d408d0 ( SPEEDBAR): same window start
0x2d408d0 ( SPEEDBAR): 1
0x13cbc30 (HELLO): same window start
0x13cbc30 (HELLO): 1
redisplay_preserve_echo_area (9)
redisplay_internal 0
expose_frame (0, 0, 170, 1026)
expose_window (1, 1, 168, 1024)
expose_line 0: (0, 0, 168, 1024)
expose_line 16: (0, 0, 168, 1024)
expose_line 32: (0, 0, 168, 1024)
expose_line 48: (0, 0, 168, 1024)
expose_line 64: (0, 0, 168, 1024)
expose_line 80: (0, 0, 168, 1024)
expose_line 96: (0, 0, 168, 1024)
expose_line 112: (0, 0, 168, 1024)
expose_line 128: (0, 0, 168, 1024)
expose_line 144: (0, 0, 168, 1024)
expose_line 160: (0, 0, 168, 1024)
expose_line 176: (0, 0, 168, 1024)
expose_line 192: (0, 0, 168, 1024)
expose_line 208: (0, 0, 168, 1024)
expose_line 224: (0, 0, 168, 1024)
expose_line 240: (0, 0, 168, 1024)
expose_line 256: (0, 0, 168, 1024)
expose_line 272: (0, 0, 168, 1024)
expose_line 288: (0, 0, 168, 1024)
expose_line 304: (0, 0, 168, 1024)
expose_line 320: (0, 0, 168, 1024)
expose_line 336: (0, 0, 168, 1024)
expose_line 352: (0, 0, 168, 1024)
expose_line 368: (0, 0, 168, 1024)
expose_line 384: (0, 0, 168, 1024)
expose_line 400: (0, 0, 168, 1024)
expose_line 416: (0, 0, 168, 1024)
expose_line 432: (0, 0, 168, 1024)
expose_line 448: (0, 0, 168, 1024)
expose_line 464: (0, 0, 168, 1024)
expose_line 480: (0, 0, 168, 1024)
expose_line 496: (0, 0, 168, 1024)
expose_line 512: (0, 0, 168, 1024)
expose_line 528: (0, 0, 168, 1024)
expose_line 544: (0, 0, 168, 1024)
expose_line 560: (0, 0, 168, 1024)
expose_line 576: (0, 0, 168, 1024)
expose_line 592: (0, 0, 168, 1024)
expose_line 608: (0, 0, 168, 1024)
expose_line 624: (0, 0, 168, 1024)
expose_line 640: (0, 0, 168, 1024)
expose_line 656: (0, 0, 168, 1024)
expose_line 672: (0, 0, 168, 1024)
expose_line 688: (0, 0, 168, 1024)
expose_line 704: (0, 0, 168, 1024)
expose_line 720: (0, 0, 168, 1024)
expose_line 736: (0, 0, 168, 1024)
expose_line 752: (0, 0, 168, 1024)
expose_line 768: (0, 0, 168, 1024)
expose_line 784: (0, 0, 168, 1024)
expose_line 800: (0, 0, 168, 1024)
expose_line 816: (0, 0, 168, 1024)
expose_line 832: (0, 0, 168, 1024)
expose_line 848: (0, 0, 168, 1024)
expose_line 864: (0, 0, 168, 1024)
expose_line 880: (0, 0, 168, 1024)
expose_line 896: (0, 0, 168, 1024)
expose_line 912: (0, 0, 168, 1024)
expose_line 928: (0, 0, 168, 1024)
expose_line 944: (0, 0, 168, 1024)
expose_line 960: (0, 0, 168, 1024)
expose_line 976: (0, 0, 168, 1024)
expose_line 992: (0, 0, 168, 1024)
expose_line 1008: (0, 0, 168, 1024)
expose_window (1, 0, 168, 0)
expose_window (1, 0, 168, 0)
expose_frame (0, 0, 818, 1026)
expose_window (1, 17, 816, 992)
expose_line 0: (0, 0, 816, 992)
expose_line 16: (0, 0, 816, 992)
expose_line 32: (0, 0, 816, 992)
expose_line 48: (0, 0, 816, 992)
expose_line 64: (0, 0, 816, 992)
expose_line 80: (0, 0, 816, 992)
expose_line 101: (0, 0, 816, 992)
expose_line 123: (0, 0, 816, 992)
expose_line 139: (0, 0, 816, 992)
expose_line 158: (0, 0, 816, 992)
expose_line 177: (0, 0, 816, 992)
expose_line 196: (0, 0, 816, 992)
expose_line 222: (0, 0, 816, 992)
expose_line 243: (0, 0, 816, 992)
expose_line 265: (0, 0, 816, 992)
expose_line 286: (0, 0, 816, 992)
expose_line 307: (0, 0, 816, 992)
expose_line 323: (0, 0, 816, 992)
expose_line 339: (0, 0, 816, 992)
expose_line 355: (0, 0, 816, 992)
expose_line 371: (0, 0, 816, 992)
expose_line 390: (0, 0, 816, 992)
expose_line 409: (0, 0, 816, 992)
expose_line 430: (0, 0, 816, 992)
expose_line 447: (0, 0, 816, 992)
expose_line 463: (0, 0, 816, 992)
expose_line 484: (0, 0, 816, 992)
expose_line 505: (0, 0, 816, 992)
expose_line 521: (0, 0, 816, 992)
expose_line 537: (0, 0, 816, 992)
expose_line 559: (0, 0, 816, 992)
expose_line 580: (0, 0, 816, 992)
expose_line 601: (0, 0, 816, 992)
expose_line 622: (0, 0, 816, 992)
expose_line 643: (0, 0, 816, 992)
expose_line 664: (0, 0, 816, 992)
expose_line 685: (0, 0, 816, 992)
expose_line 706: (0, 0, 816, 992)
expose_line 728: (0, 0, 816, 992)
expose_line 747: (0, 0, 816, 992)
expose_line 766: (0, 0, 816, 992)
expose_line 787: (0, 0, 816, 992)
expose_line 806: (0, 0, 816, 992)
expose_line 822: (0, 0, 816, 992)
expose_line 838: (0, 0, 816, 992)
expose_line 857: (0, 0, 816, 992)
expose_line 879: (0, 0, 816, 992)
expose_line 898: (0, 0, 816, 992)
expose_line 917: (0, 0, 816, 992)
expose_line 938: (0, 0, 816, 992)
expose_line 959: (0, 0, 816, 992)
expose_line 975: (0, 0, 816, 992)
expose_line 976: (0, 0, 816, 992)
expose_window (1, 1009, 816, 16)
expose_line 0: (0, 0, 816, 16)
expose_window (1, 16, 816, 0)
expose_window (1, 0, 816, 16)
expose_line 0: (0, 0, 816, 16)

One more piece of information: once Emacs gets into `bad' mode,
switching out of the virtual desktop then coming back in several times
won't turn Emacs into `good' mode.  The way I used to recover was to
switch to another Emacs buffer then switch back.  Also, it is
interesting to see that a few seconds after seeing a completely blank
`bad' Emacs frame, a few lines of glyphs show up.