Without an explicit size the layout system does not have enough
constraints to produce nice looking dialogs. Up until now the workaround
was to set explicit an size for some of the widget. This worked well
enough except when resizing down the window up until the widget size
constraints could no longer be enforced. At that point, produced layouts
looked too squished.
Previously it was only possible to specify whether items where aligned
to the start or centered in the cross direction of the layouts. It is
now additionally possible to align the items to the far end of the cross
direction or to resize them to match the size of the layout.
Terminology and behavior are loosely based on CSS's flexbox containers.
Prior to this change, a GUI layout was only affected by the screen size.
Now, a layout can additionally be influenced by the GUI dialog and widgets
that uses it. This capability is leveraged to implement the following
features:
* Layout elements that are not bound to a GUI widget do not take space.
This means that dialogs where the widgets shown depend on for example
a feature being enabled at configure time no longer have blank spaces.
* Widgets can define a minimal required size for their contents not to be
cut. For now this is only used for buttons so their width is always
sufficient for their caption not to be cut. This mechanism could be
applied to other widget types in the future.
- Split out label from PopUp widget
- Aligned every widget on all layouts so GUI becomes to look nice again
- Moved textHAlign to layout properties
svn-id: r41266
