While in adjustment brush, the keyboard shortcut for A/B change malfunctions after any development slider is changed and the mouse cursor still hovers over the changed slider.
The malfunction depends on the language: If the A/B-change shortcut has another meaning, that is executed. If not, nothing happens and the shortcut works when pressing it another time.
Example: In English GUI, A/B-change is the "/" key, but it has also the meaning "deselect active photo". So, to reproduce in english: 1. Enter adjustment brush 2. Draw some brush strokes 3. Change some slider (e.g. exposure of the brush itself), don't move mouse away from slider! 4. Press / Expected result: Brush changes from A to B or vice versa Actual result: Edited photo is deselected and "no photo selected" is displayed.
Lightroom 4.1 RC 64 Bit, Windows 7. In Lightroom 3.6, the bug does not appear.
P.S. Same as the other bug: Of course only a minor one, but can be irritating 😉