So, there should be a method to select many controls by Ctrl-Click and edit their parameters together. (It is done this way in Delphi and Freepascal/Lazarus). This would be a great improvement and speed up the editing.
I have now tried wxCrafter, wxFormbuilder, DialogBlocks and wxSmith, but none has this ability.
Indeed, none has that ability; and, as the saying goes, "It's not a bug, it's a feature".
In this case it is a missing feature. It is just an editing feature that would be compatible with the sizer based design.
Those form designers are meant for creating wxWidgets programs. wxWidgets' sizer system lets you avoid the disadvantages of absolute positioning e.g. they painlessly cope with a change of font-size or locale.
To be fair, one must admit, in Freepascal/Delphi there is relative positioning. Controls or panels are "anchored" to relative window positions or to other controls and there are font dependent mechanisms to take care of font size or of High DPI displays.
Alignment is achieved with editing functions, Ctrl-Click many controls and choose to align them.
I have also tried "Ultimate++", they use fontsized coordinates and a system of solid and elastic spacers, which is MUCH more intuitive and flexible. They also have this Ctrl click feature to edit many controls simultaniously. (I dont use it, because they use an own package and documentation systen, that binds you to their IDE, build system and "NTL" which replaces the STL.)
I dont use Delphi/Freepascal, because I want C++, not Pascal.