T400 screen resolution with external monitor, with or without Mini-Dock

When I connect an external monitor to the T400 directly (VGA connection) or to the Thinkpad Mini-Dock via VGA, it works but with a resolution of 1920x1080 although the monitor supports 2560x1440.

I have another external monitor that have DVI so I tried connecting it to the Mini-Dock via DVI but it is not detected at all.

With the X200 and its Docking Station, there is a DisplayPort connector and then, on the same monitor, I can get 2560x1440, so perhaps the same could be done in some way with the T400?

sudo lshw -c video says:
*-display:0
description: VGA compatible controller
product: Mobile 4 Series Chipset Integrated Graphics Controller
vendor: Intel Corporation
physical id: 2
bus info: pci@0000:00:02.0
logical name: /dev/fb0
version: 07
width: 64 bits
clock: 33MHz
capabilities: msi pm vga_controller bus_master cap_list rom fb
configuration: depth=32 driver=i915 latency=0 resolution=1440,900
resources: irq:16 memory:94000000-943fffff memory:a0000000-afffffff ioport:1100(size=8) memory:c0000-dffff
*-display:1 UNCLAIMED
description: Display controller
product: Mobile 4 Series Chipset Integrated Graphics Controller
vendor: Intel Corporation
physical id: 2.1
bus info: pci@0000:00:02.1
version: 07
width: 64 bits
clock: 33MHz
capabilities: pm cap_list
configuration: latency=0
resources: memory:98500000-985fffff
It seems the Intel integrated graphics controller have some additional display that is "UNCLAIMED" so I guess there is no driver for it. I don't know what that "display:1" could be useful for.