> A strong GUI editor that works with (mostly) zero configuration is a big feature of VB6 to me.
IMO even Delphi 1 had a better GUI form designer. The "Align" property that many controls had, including containers, allowed for visually creating resizable layouts easily since that placed a control to one of the left, right, top and bottom edges of its parent (multiple controls could be stacked) or at the "client" area which basically covered the remaining area. VB had a similar property but IIRC only the picture control supported it (the picture control was also used as a container) and could only place controls to the edges but not the client area. This meant that pretty much any non-trivial UI that needed a resizable window had custom code for the resizing event to handle that instead of being done visually.
Delphi later added a simple "anchor" property to allow custom placed controls to be resized too (the default setting was to anchor to the left and top edge which behaved like before anchors were introduced, but e.g. anchoring a control to the right edge in addition to the left caused the control to be resized horizontally when its parent was resized and anchoring it only on the right caused it instead to move horizontally).
Nowadays Lazarus provides a more advanced anchoring system (e.g. you can have a label control be aligned vertically at the middle of a combo box control and the combo box's left edge to be aligned with the label's right edge with a margin of 5 pixels) which is set up using a visual editor (no code needed) but it also provides the Delphi-like anchors and align properties as well as a bunch of other properties that can be edited visually, like min/max sizes, child control placement, etc all of which make it IMO by far the best WYSIWYG form designer for desktop GUIs (though the anchor editor's own UX could be improved).
IMO even Delphi 1 had a better GUI form designer. The "Align" property that many controls had, including containers, allowed for visually creating resizable layouts easily since that placed a control to one of the left, right, top and bottom edges of its parent (multiple controls could be stacked) or at the "client" area which basically covered the remaining area. VB had a similar property but IIRC only the picture control supported it (the picture control was also used as a container) and could only place controls to the edges but not the client area. This meant that pretty much any non-trivial UI that needed a resizable window had custom code for the resizing event to handle that instead of being done visually.
Delphi later added a simple "anchor" property to allow custom placed controls to be resized too (the default setting was to anchor to the left and top edge which behaved like before anchors were introduced, but e.g. anchoring a control to the right edge in addition to the left caused the control to be resized horizontally when its parent was resized and anchoring it only on the right caused it instead to move horizontally).
Nowadays Lazarus provides a more advanced anchoring system (e.g. you can have a label control be aligned vertically at the middle of a combo box control and the combo box's left edge to be aligned with the label's right edge with a margin of 5 pixels) which is set up using a visual editor (no code needed) but it also provides the Delphi-like anchors and align properties as well as a bunch of other properties that can be edited visually, like min/max sizes, child control placement, etc all of which make it IMO by far the best WYSIWYG form designer for desktop GUIs (though the anchor editor's own UX could be improved).