Problem dynamic stretch not-vertical lines!

[vasilev7F5S5]

Hi everyone, 

i´m not so gut with dynamic blocks and i need your help.
In my case (see attached file) I made dynamic block with Stretch action for vertical and horizontal direction. 
Vertical Stretch works perfect, but what to do with horizontal  i really do not know.

I need to have the top vertex of the red polyline always in the middle of the upper white line.

But it does not work.

How can I fix it?

[j.palmeL29YX]

You need two Stretch Actions for the horizontal movement. One of them stretches only the right side of the geometry, the other stretches the top of the triangle with a Distance Multiplicator of 0.5. 

Additional hint: I'd suggest to set the number of grips for the two Linear Parameter to 1. 

[vasilev7F5S5]

Hello Jürgen, thanks for the answer, but I can´t repeat your solution.
I do not undestand the step on 1:37 from the video.
What do you press to make your mouspoint blue and then go to the menu for Multiplier?

[h_s_walker · Accepted solution]

Multiplier needs to be 0.5 so that the red lines stay in the middle of the rectangle. See the image below for another view

[j.palmeL29YX · Accepted solution]

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@vasilev7F5S5 wrote:

What do you press to make your mouspoint blue and then go to the menu for Multiplier?

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Sorry for missing this explanation. The green rings are a left mouse click, the blue rings are a right mouse click. And in my Options -> User Preferences -> Right Click Customization the time-sensitive right-click is turned ON => a right click (in my video(s) the blue rings) do the same as an ENTER or pressing the Space key. 

In my video at 1:37 the blue rings end the object selection and go to the next step in the Bactiontool command. 

An other way: If you later want or need to change the value of the Distance Multiplier, select the stretch command, activate the properties panel and edit the value in the Overrides section. (As shown by @h_s_walker above)

[vasilev7F5S5]

Thanks so much!
Now its working!