- TIA Version including SP / upd : 

Tia Portal V14 Update 2

- Hardware identification :

TP1900 Comfort

- Application description (scenario):

I had a HMI design in Tia Portal V13 SP1 for an industry standard. Now we stepped over from V13 SP1 to V14 upd 2. In the HMI we had a Symbolic IO Field used as a drop down list to make a selection from. This Symbolic IO Field is linked to an Index variable and a Text list to make a selection from.

Now with V14 Upd 2 we have a problem with this drop down list. I can no longer make a selection from it with my LMB. Once I click on the Symbolic IO Field and release, it automaticly close again. This behavior is totally different from V13 SP1, where it would just show the list and only close it after you made a selection. Now to make a selection I have to hold LMB to open the list and meanwhile click RMB to make a selection, ofc this isn't functional because it will be used on a touchpanel.

My question, is it possible in V14 Upd 2 to make it behave the same? So that a Symbolic IO Field can be opened with one click and make a selection with another LMB click( like in V13). Or is this a problem with the current update? 

The problem also exists in WinCC V14 SP1.  I cannot use WinCC V14 if the symbolic I/O field does not function properly. 

I had to use V13 SP1 Upd9 (I did not upgrade to V13 SP2 yet).

I've attached a video that shows the problem. 

When you see the Symbolic I/O field open and close right away, I am only left-clicking once on it.

When you see the symbolic I/O field staying open, I am left-clicking on it, and while holding the left mouse button, I move the cursor over the scroll bar. Only then am I able to click on a value (a/b/c) to select the value I want.  At no other time, does the Symbolic I/O field stay open.

This is a bug that needs to be fixed by Siemens.

PS: I am using WinCC Advanced RT V14 SP1

Wow.. this worked, but it's a pretty poor design to depend on a Windows setting for such a thing.  My usual habit in Windows is to adjust settings for "Best Performance" so that the computer runs quicker... I would have never thought it would affect the operation of HMI software, and it never has in the past, until now.

More surprising is that this Windows setting "slide open comboboxes" has no effect on WinCC V13 (SP1 Upd9)... which begs the question... why the design change???  This is a pretty obscure solution, which no one would figure out without inside knowledge of the development of WinCC, or an FAQ on the topic.  Once again, another frustrating experience in Siemens migrations/upgrades!

PS: For those who can't see the attachment with the solution:

Right-click Computer
Properties
Advanced system settings
Performance Settings
Check the box for "Slide open comboboxes"

 Hello Everyone,

I have same problem with Tia v14 SP1 and i've tried to follow these steps but the problem is still there.

Contrologica

Wow.. this worked, but it's a pretty poor design to depend on a Windows setting for such a thing.  My usual habit in Windows is to adjust settings for "Best Performance" so that the computer runs quicker... I would have never thought it would affect the operation of HMI software, and it never has in the past, until now.

More surprising is that this Windows setting "slide open comboboxes" has no effect on WinCC V13 (SP1 Upd9)... which begs the question... why the design change???  This is a pretty obscure solution, which no one would figure out without inside knowledge of the development of WinCC, or an FAQ on the topic.  Once again, another frustrating experience in Siemens migrations/upgrades!

PS: For those who can't see the attachment with the solution:

Right-click Computer
Properties
Advanced system settings
Performance Settings
Check the box for "Slide open comboboxes"