Fix `DragValue` expansion when editing (#5809)

* [x] I have followed the instructions in the PR template

This PR fixes an issue, where `DragValue` would expand when it enters
editing state. There were 3 contributing problems:
- A workaround introduced in #4276 caused the `DragValue` to report
incorrect outer size.
- The `DragValue` uses `TextEdit` internally and sets both `min_size`
and `desired_width` to the same value - desired width is used **before**
padding is applied - this is in contrast to `Button` (also used
internally by `DragValue`), which only uses `min_size`. This caused the
`DragValue` to expand horizontally by the size of button padding.
- The height of the `TextEdit` is (among other things) determined by the
height of the row, which was not present in `Button`. This caused a
small vertical expansion, when the contents (including padding) were
larger than the `min_size`.


![egui_drag_value_expansion](https://github.com/user-attachments/assets/b6fe9bd8-5755-4a43-8b61-a7e5b24e678d)
Here the dimensions set in code are:
- padding: 20 x 20 pt
- interact size: 80 x 30 pt

*Note: I do not know what's up with the tests. When I ran the check
script, they were failing because of 3 UI missmatches, so I updated the
snapshots. Now, the updated snapshots cause the same failure in CI, that
appeared locally before the update. Now the locally run tests fail with
`The platform you're compiling for is not supported by winit` and couple
more following errors coming from the same source (`winit 0.30.7`).*

crates/egui/src/widgets/button.rs

@@ -1,6 +1,6 @@
 use crate::{
-    widgets, Align, Color32, CornerRadius, Image, NumExt, Rect, Response, Sense, Stroke, TextStyle,
-    TextWrapMode, Ui, Vec2, Widget, WidgetInfo, WidgetText, WidgetType,
+    widgets, Align, Color32, CornerRadius, FontSelection, Image, NumExt, Rect, Response, Sense,
+    Stroke, TextStyle, TextWrapMode, Ui, Vec2, Widget, WidgetInfo, WidgetText, WidgetType,
 };
 
 /// Clickable button with text.
@@ -224,6 +224,16 @@ impl Widget for Button<'_> {
 
         let frame = frame.unwrap_or_else(|| ui.visuals().button_frame);
 
+        let default_font_height = || {
+            let font_selection = FontSelection::default();
+            let font_id = font_selection.resolve(ui.style());
+            ui.fonts(|f| f.row_height(&font_id))
+        };
+
+        let text_font_height = ui
+            .fonts(|fonts| text.as_ref().map(|wt| wt.font_height(fonts, ui.style())))
+            .unwrap_or_else(default_font_height);
+
         let mut button_padding = if frame {
             ui.spacing().button_padding
         } else {
@@ -233,11 +243,17 @@ impl Widget for Button<'_> {
             button_padding.y = 0.0;
         }
 
-        let space_available_for_image = if let Some(text) = &text {
+        let (space_available_for_image, right_text_font_height) = if let Some(text) = &text {
             let font_height = ui.fonts(|fonts| text.font_height(fonts, ui.style()));
-            Vec2::splat(font_height) // Reasonable?
+            (
+                Vec2::splat(font_height), // Reasonable?
+                font_height,
+            )
         } else {
-            ui.available_size() - 2.0 * button_padding
+            (
+                ui.available_size() - 2.0 * button_padding,
+                default_font_height(),
+            )
         };
 
         let image_size = if let Some(image) = &image {
@@ -283,11 +299,14 @@ impl Widget for Button<'_> {
         }
         if let Some(galley) = &galley {
             desired_size.x += galley.size().x;
-            desired_size.y = desired_size.y.max(galley.size().y);
+            desired_size.y = desired_size.y.max(galley.size().y).max(text_font_height);
         }
         if let Some(right_galley) = &right_galley {
             desired_size.x += gap_before_right_text + right_galley.size().x;
-            desired_size.y = desired_size.y.max(right_galley.size().y);
+            desired_size.y = desired_size
+                .y
+                .max(right_galley.size().y)
+                .max(right_text_font_height);
         }
         desired_size += 2.0 * button_padding;
         if !small {

crates/egui/src/widgets/drag_value.rs

@@ -562,7 +562,9 @@ impl Widget for DragValue<'_> {
                     .margin(ui.spacing().button_padding)
                     .min_size(ui.spacing().interact_size)
                     .id(id)
-                    .desired_width(ui.spacing().interact_size.x)
+                    .desired_width(
+                        ui.spacing().interact_size.x - 2.0 * ui.spacing().button_padding.x,
+                    )
                     .font(text_style),
             );
 

crates/egui/src/widgets/text_edit/builder.rs

@@ -426,18 +426,11 @@ impl TextEdit<'_> {
         let background_color = self
             .background_color
             .unwrap_or(ui.visuals().extreme_bg_color);
-        let margin = self.margin;
-        let mut output = self.show_content(ui);
-
-        // TODO(emilk): return full outer_rect in `TextEditOutput`.
-        // Can't do it now because this fix is ging into a patch release.
-        let outer_rect = output.response.rect;
-        let inner_rect = outer_rect - margin;
-        output.response.rect = inner_rect;
+        let output = self.show_content(ui);
 
         if frame {
             let visuals = ui.style().interact(&output.response);
-            let frame_rect = outer_rect.expand(visuals.expansion);
+            let frame_rect = output.response.rect.expand(visuals.expansion);
             let shape = if is_mutable {
                 if output.response.has_focus() {
                     epaint::RectShape::new(