Fix multiple issues with textbox content display

- Sometimes would display too many decimal digits due to floating point
  representation errors.

- Placeholder would also look wrong if text was removed during a
  multiple (but determinate) selection.

osu.Game/Graphics/UserInterface/OsuSliderBar.cs

@@ -19,6 +19,7 @@
 using osu.Framework.Localisation;
 using osu.Framework.Utils;
 using osu.Game.Overlays;
+using osu.Game.Utils;
 
 namespace osu.Game.Graphics.UserInterface
 {
@@ -219,7 +220,7 @@ private void updateTooltipText(T value)
                     decimal decimalPrecision = normalise(CurrentNumber.Precision.ToDecimal(NumberFormatInfo.InvariantInfo), max_decimal_digits);
 
                     // Find the number of significant digits (we could have less than 5 after normalize())
-                    int significantDigits = findPrecision(decimalPrecision);
+                    int significantDigits = FormatUtils.FindPrecision(decimalPrecision);
 
                     TooltipText = floatValue.ToString($"N{significantDigits}");
                 }
@@ -248,23 +249,5 @@ protected override void UpdateValue(float value)
         /// <returns>The normalised decimal.</returns>
         private decimal normalise(decimal d, int sd)
             => decimal.Parse(Math.Round(d, sd).ToString(string.Concat("0.", new string('#', sd)), CultureInfo.InvariantCulture), CultureInfo.InvariantCulture);
-
-        /// <summary>
-        /// Finds the number of digits after the decimal.
-        /// </summary>
-        /// <param name="d">The value to find the number of decimal digits for.</param>
-        /// <returns>The number decimal digits.</returns>
-        private int findPrecision(decimal d)
-        {
-            int precision = 0;
-
-            while (d != Math.Round(d))
-            {
-                d *= 10;
-                precision++;
-            }
-
-            return precision;
-        }
     }
 }

osu.Game/Screens/Edit/Timing/IndeterminateSliderWithTextBoxInput.cs

@@ -2,6 +2,7 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using System;
+using System.Globalization;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
@@ -9,6 +10,7 @@
 using osu.Framework.Localisation;
 using osu.Game.Graphics.UserInterfaceV2;
 using osu.Game.Overlays.Settings;
+using osu.Game.Utils;
 
 namespace osu.Game.Screens.Edit.Timing
 {
@@ -65,7 +67,6 @@ public IndeterminateSliderWithTextBoxInput(LocalisableString labelText, Bindable
                         textbox = new LabelledTextBox
                         {
                             Label = labelText,
-                            PlaceholderText = "(multiple)"
                         },
                         slider = new SettingsSlider<T>
                         {
@@ -104,11 +105,16 @@ private void updateState()
             if (Current.Value is T nonNullValue)
             {
                 slider.Current.Value = nonNullValue;
-                textbox.Text = slider.Current.ToString();
+
+                // use the value from the slider to ensure that any precision/min/max set on it via the initial indeterminate value have been applied correctly.
+                decimal decimalValue = slider.Current.Value.ToDecimal(NumberFormatInfo.InvariantInfo);
+                textbox.Text = decimalValue.ToString($@"N{FormatUtils.FindPrecision(decimalValue)}");
+                textbox.PlaceholderText = string.Empty;
             }
             else
             {
                 textbox.Text = null;
+                textbox.PlaceholderText = "(multiple)";
             }
         }
     }

osu.Game/Utils/FormatUtils.cs

@@ -31,5 +31,23 @@ public static LocalisableString FormatAccuracy(this double accuracy)
         /// </summary>
         /// <param name="rank">The rank/position to be formatted.</param>
         public static string FormatRank(this int rank) => rank.ToMetric(decimals: rank < 100_000 ? 1 : 0);
+
+        /// <summary>
+        /// Finds the number of digits after the decimal.
+        /// </summary>
+        /// <param name="d">The value to find the number of decimal digits for.</param>
+        /// <returns>The number decimal digits.</returns>
+        public static int FindPrecision(decimal d)
+        {
+            int precision = 0;
+
+            while (d != Math.Round(d))
+            {
+                d *= 10;
+                precision++;
+            }
+
+            return precision;
+        }
     }
 }