I have done some limited testing, and this is what I have found.
Windows 10 is pretty good on remembering the Save As dialog size per
application, so one does no longer need the old trick of holding
Ctrl while closing the dialog.
Windows 10 will remember your selected columns across applications,
but not the size. For keeping these sizes you need a third party product.
A shareware product that keeps sizes and more is Direct Folders ($19.95). However there is a free method.
Using the free macro language AutoHotkey, one can create a macro that
checks every second for a dialog containing in its title "Save As" or "Open"
and resizes it to a given size.
Here is such a macro (source) which you could tailor to your needs :
#Persistent
SetTimer, MyTimer, 1000
return
MyTimer:
SetTitleMatchMode, 3
WinMove, Save As,,340,170,800,600
WinMove, Open,,340,170,800,600
return
Note that newer Office programs have their own separate methods for
these dialogs.
References :
Interesting... but how much CPU resources would that instant check consumes? – FernandoSBS – 2017-04-30T13:03:48.487
Very little - AutoHotkey is very efficient and is the building language for many useful products. – harrymc – 2017-04-30T16:19:02.053
can I set the size for both the folder tree and the files part? – FernandoSBS – 2017-04-30T20:14:34.007
I'm sure you can, as one can do almost everything with AHK, but I'm not an advanced enough user. – harrymc – 2017-05-01T06:36:08.270
I have opened the documentation for WinMove and it doesn't have option for folder three, unfortunately... is there any other command related to window settings? – FernandoSBS – 2017-05-04T15:38:33.200
The tree is a Windows object, essentially a child window of the parent Explorer window. You need to identify it in order to operate upon it. Explaining how to do that is too heavy for me to do it here. You will need to become an advanced user of AHK. – harrymc – 2017-05-04T15:44:27.723
Could you just send the code that I should use? – FernandoSBS – 2017-05-04T19:31:22.650
Sorry, that would take more time than I have available. What you could do as a way to speed-up the writing of such macros, is to use a macro-recorder for AHK that will record the actions you do with the mouse to resize the tree, then modify the macro to make it more general. Try the old
– harrymc – 2017-05-04T19:51:46.503AutoScriptWriter.exe
in the AHK folder, or the newer Macro Creator. You will need to learn AHK, no help for it. See for example this tutorial.