xrandr --delmode unable to remove incorrectly detected video resolution modes

[pureblood]

I own an HP LP3065 monitor (http://www.amazon.com/dp/B000KB6E3G/) with a BizLink displayport adapter (http://www.amazon.com/dp/B003XYBA72/). The command "sudo get-edid -b 6 | parse-edid" correctly identifies the available resolutions of the screen as 2560x1600 and 1280x800. However, the Ubuntu system incorrectly identifies instead the resolutions 1024x768, 800x600, 848x480, and 640x480 which all don't work with the monitor. While I have to add manually the correct resolutions with xrandr using the command "xrandr --newmode 2560x1600 268.00 2560 2608 2640 2720 1600 1603 1609 1646 -hsync +vsync && xrandr --addmode DP1 2560x1600", I occasionally have the system attempting to use the 1024x768 resolution leading to an empty black screen. One potential solution would be to remove the rogue resolutions so that they could not be automatically chosen. I tried the command "xrandr --delmode DP1 1024x768" but this is to no avail with the following output:
X Error of failed request: BadAccess (attempt to access private resource denied)
  Major opcode of failed request: 140 (RANDR)
  Minor opcode of failed request: 19 (RRDeleteOutputMode)
  Serial number of failed request: 42
  Current serial number in output stream: 43
My understanding is that the system thinks to know better than the user and disallows from removing native resolutions. However, it is clear that the system is not designed well enough to know what the correct native resolutions are. This is tremendously frustrating and ultimately it is combination of a bug in properly detecting the native resolutions (gone unfixed for the last five years) and a flawed design assuming detected resolutions would never need to be removed. I am at a loss with regard who to and where to file this bug. I would be tremendously grateful to anybody who could provide some directions.

[pureblood (freeseek)]

With Ubuntu 15.04 and the newest 4.1.0-040100rc1-generic kernel, the system now correctly identifies the available resolutions.