The shabbat before the 9th of Av is called Shabbat Hazon. It is named for the first word of the haftarah, the first chapter of Isaiah, Chazon (vision) of Yishayahu/Isaiah. The last Lubavitcher Rebbe, ztz"l, put it that we ought not to consider this shabbat a mournful day. First of all, mourning is inappropriate for shabbat, and second he felt it should be a day of motivation towards a more positive future. I wonder whether his idea might stem from a frequent Jewish practice. We frequently diminish the joy of a positive occasion, removing a drop of wine as we recite each plague at the Pesach seder, there is a fast of the first born before Pesach and of Esther before Purim. I am inclined to see the Rebbe's slant on Shabbat Chazon as seeking the same sort of balance by taking from the full cup of bitterness tisha b'av represents.
I learned an interesting lesson recently regarding Rashi's commentary. When he says he is explaining according to the plain meaning of the text ("Pshat"), Rashi frequently seems to me to involve some imaginative story. For example, he says at one point that Sarah was rewarded with renewed youth and breasts swollen with milk, and she suckled all the children that came to Isaac's weaning. I took this to be fairly fanciful. Does anyone else remember the Chinese policewoman during the last big earthquake there, who left her baby with her mom, and found nursing about a dozen babies, saving their lives by the way, was the most effective emergency aid she could render. In other words, there's no reason Sarah couldn't have done the same. Silly me.