LibGUI: Rewrite layout system in terms of min and max sizes

This patch removes size policies and preferred sizes, and replaces them
with min-size and max-size for each widget.

Box layout now works in 3 passes:

    1) Set all items (widgets/spacers) to their min-size
    2) Distribute remaining space evenly, respecting max-size
    3) Place widgets one after the other, adding spacing in between

I've also added convenience helpers for setting a fixed size (which is
the same as setting min-size and max-size to the same value.)

This significantly reduces the verbosity of widget layout and makes GML
a bit more pleasant to write, too. :^)

2 files changed, 2 insertions, 4 deletions

diff --git a/DevTools/Profiler/ProfileTimelineWidget.cpp b/DevTools/Profiler/ProfileTimelineWidget.cpp
index 025af2c5f9..bbaf38973f 100644
--- a/DevTools/Profiler/ProfileTimelineWidget.cpp
+++ b/DevTools/Profiler/ProfileTimelineWidget.cpp
@@ -33,8 +33,7 @@ ProfileTimelineWidget::ProfileTimelineWidget(Profile& profile)
 {
     set_background_color(Color::White);
     set_fill_with_background_color(true);
-    set_size_policy(GUI::SizePolicy::Fill, GUI::SizePolicy::Fixed);
-    set_preferred_size(0, 80);
+    set_fixed_height(80);
 }
 
 ProfileTimelineWidget::~ProfileTimelineWidget()
diff --git a/DevTools/Profiler/main.cpp b/DevTools/Profiler/main.cpp
index 38f3ebc3ee..fb157979e8 100644
--- a/DevTools/Profiler/main.cpp
+++ b/DevTools/Profiler/main.cpp
@@ -176,8 +176,7 @@ static bool prompt_to_stop_profiling(pid_t pid, const String& process_name)
     });
 
     auto& stop_button = widget.add<GUI::Button>("Stop");
-    stop_button.set_size_policy(GUI::SizePolicy::Fixed, GUI::SizePolicy::Fixed);
-    stop_button.set_preferred_size(140, 22);
+    stop_button.set_fixed_size(140, 22);
     stop_button.on_click = [&](auto) {
         GUI::Application::the()->quit();
     };