VNC: rotated touchscreen input with multiple monitor settings

[SuperPT]

Hello,
I'm developing an embedded application that works on a linux board using QT 4.8.5. To view it correctly I have to rotate the screen because it is mounted vertically on the board. I obtained this settings the QWS_DISPLAY variable as following:

export QWS_DEPTH=24
export QWS_DISPLAY=Transformed:Rot90

export QWS_DEPTH=24
export QWS_DISPLAY=Transformed:Rot90

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Now I need to control it from remote with a vnc connection, to see the application correctly I have to set a multi monitor to have the screen of the vnc on the original orientation and the embedded screen rotated by 90°, therefore I modified the QWS_DISPLAY variable as following:

export QWS_DEPTH=24
export QWS_DISPLAY="Multi: VNC:size=576x720:0  Transformed:Rot90:1"

export QWS_DEPTH=24
export QWS_DISPLAY="Multi: VNC:size=576x720:0  Transformed:Rot90:1"

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With these settings the visualization is good both on the client and on the display, the inputs on the VNC client works fine, but on the touchscreen display the inputs are rotated by 90°.
How can I set QWS_DISPLAY to fix it?