So there have been several bugs that I have come across in the editor and I am unsure on whether or not all of them have been reported so I am just gonna gather all of them here. (In my knowledge)
Straight anchor: Client crashes if an anchor is being placed in the middle of a straight slider (not altering the sliderbody) and do Ctrl+G on that slider. Fixed
Special characters: I have been getting errors while trying to upload or update beatmap sets that include special characters (*,`,^) in their title.
Going above: If you Ctrl+C a stream (overlapping hit-circles), paste it elsewhere and do Ctrl+G, the hit-objects overlap in the wrong order. Fixed
Disappearing stuff: Copying and pasting a group of objects they are getting selected by default after pasting. However if you scroll though the time-line, only some of them remain highlighted and but can still be clicked and dragged across the screen.
Far crash: Client usually crashes when double clicking (to transit onto it's time) on an object that is more than 1 or 2 minutes away in the timeline. (This usually occurs on low-end computers and has been tested repeatedly).
Extra difficulty: It rarely happens but if you change the timing of a beatmap and save it, a new difficulty is created that is usually only in-game and does not exist on the osu! folders as a .osu file. It might or might not go away if you refresh but it will go away if you restart the client.
Huge sliders: Again, it's pretty rare but the client crashes when moving a middle anchor in a way that would create something like this.
Update:
Extra control: While in the editor and with the in-game chat on, it's still possible to scroll across the time-line if the cursor is on the transparent white border.
Silent Slider-Ends: Why having AiMod open and the beatmap progressing in the background, the slider-ends become silenced.
Placing hit-circle: If the hit-circle add tool is selected, while verifying the changes on the Song Setup panel, the hit-circle (that still moves along with the cursor) will be placed down in the mapping area.
White ends: This Happened white doing some Ctrl+G work. Unsure of what exactly is the cause. (Version: b20151110.10cuttingedge)
osu! version: 20151016.8 (latest)
Straight anchor: Client crashes if an anchor is being placed in the middle of a straight slider (not altering the sliderbody) and do Ctrl+G on that slider. Fixed
Special characters: I have been getting errors while trying to upload or update beatmap sets that include special characters (*,`,^) in their title.
Going above: If you Ctrl+C a stream (overlapping hit-circles), paste it elsewhere and do Ctrl+G, the hit-objects overlap in the wrong order. Fixed
Disappearing stuff: Copying and pasting a group of objects they are getting selected by default after pasting. However if you scroll though the time-line, only some of them remain highlighted and but can still be clicked and dragged across the screen.
Far crash: Client usually crashes when double clicking (to transit onto it's time) on an object that is more than 1 or 2 minutes away in the timeline. (This usually occurs on low-end computers and has been tested repeatedly).
Extra difficulty: It rarely happens but if you change the timing of a beatmap and save it, a new difficulty is created that is usually only in-game and does not exist on the osu! folders as a .osu file. It might or might not go away if you refresh but it will go away if you restart the client.
Huge sliders: Again, it's pretty rare but the client crashes when moving a middle anchor in a way that would create something like this.
Update:
Extra control: While in the editor and with the in-game chat on, it's still possible to scroll across the time-line if the cursor is on the transparent white border.
Silent Slider-Ends: Why having AiMod open and the beatmap progressing in the background, the slider-ends become silenced.
Placing hit-circle: If the hit-circle add tool is selected, while verifying the changes on the Song Setup panel, the hit-circle (that still moves along with the cursor) will be placed down in the mapping area.
White ends: This Happened white doing some Ctrl+G work. Unsure of what exactly is the cause. (Version: b20151110.10cuttingedge)
osu! version: 20151016.8 (latest)