diff --git a/crates/ui-egui/src/dimension_create_ui_tests.rs b/crates/ui-egui/src/dimension_create_ui_tests.rs
index 7cfd1910..fc013b22 100644
--- a/crates/ui-egui/src/dimension_create_ui_tests.rs
+++ b/crates/ui-egui/src/dimension_create_ui_tests.rs
@@ -26,8 +26,39 @@ fn place(h: &mut Harness, picks: &[[f64; 2]], at: [f64; 2]) {
 }
 fn type_value(h: &mut Harness, text: &str) {
     h.step(&json!({"key":"A","cmd":true})).unwrap();
-    h.step(&json!({"text":text})).unwrap();
+    if text.is_empty() {
+        h.step(&json!({"key":"Backspace"})).unwrap();
+    } else {
+        h.step(&json!({"text":text})).unwrap();
+    }
 }
+#[test]
+fn dimension_parameters_use_typing_and_ctrl_space_completion() {
+    for (prefix, expected) in [("wid", "width"), ("", "width"), ("d", "d1")] {
+        let mut h = line([20., 0.]);
+        h.app.run("parameters.add", json!({"name":"width","expression":"25 mm"})).unwrap();
+        if prefix == "d" {
+            h.app.run("sketch.line", json!({"points":[[0,-10],[12,-10]],"infer":false})).unwrap();
+            h.app.run("sketch.dimension", json!({"entities":["l2"],"value":12,"text_at":[6,-16]})).unwrap();
+            h.settle();
+        }
+        place(&mut h, &[[10., 0.]], [10., 6.]);
+        let baseline = h.app.session.doc.to_json();
+        type_value(&mut h, prefix);
+        if prefix.is_empty() {
+            h.step(&json!({"key":"Space","cmd":true})).unwrap();
+        }
+        assert!(h.widget(expected).is_some(), "parameter completion is available for {prefix:?}: {}", h.call("ui.inspect", json!({})));
+        h.step(&json!({"key":"Tab"})).unwrap();
+        assert!(crate::dim_view::editing(), "accepting completion does not apply the dimension");
+        assert_eq!(h.app.session.doc.to_json(), baseline);
+        h.step(&json!({"key":"Enter"})).unwrap();
+        assert!(!crate::dim_view::editing());
+        assert_eq!(h.app.session.doc.params.iter().rev().find(|p| p.model).unwrap().expr, expected);
+        crate::dim_view::cancel();
+    }
+}
+
 #[test]
 fn edge_and_endpoint_creation_commit_once_and_undo_restores_exact_design() {
     for (end, picks, at) in [
diff --git a/crates/ui-egui/src/expression_complete.rs b/crates/ui-egui/src/expression_complete.rs
index 26df7cd5..67388312 100644
--- a/crates/ui-egui/src/expression_complete.rs
+++ b/crates/ui-egui/src/expression_complete.rs
@@ -2,7 +2,7 @@
 
 use egui::{Key, RichText};
 
-use crate::params_dialog::{suggestions, word_before};
+use crate::params_dialog::{suggestions_for, word_before};
 use crate::theme::Tokens;
 
 #[derive(Clone)]
@@ -15,6 +15,7 @@ struct Popup {
     count: usize,
     accept: bool,
     dismissed: bool,
+    explicit: bool,
 }
 
 fn popup_id() -> egui::Id {
@@ -25,6 +26,17 @@ fn popup_id() -> egui::Id {
 /// owns these keys. Raw events are removed too: several expression editors inspect raw Tab.
 pub(crate) fn begin_frame(ctx: &egui::Context) {
     let Some(mut popup) = ctx.data(|d| d.get_temp::<Popup>(popup_id())) else { return };
+    if ctx.memory(|m| m.has_focus(popup.editor))
+        && popup.frame.saturating_add(1) >= ctx.cumulative_frame_nr()
+        && ctx.input_mut(|i| i.consume_key(egui::Modifiers::CTRL, Key::Space))
+    {
+        ctx.input_mut(|i| {
+            i.raw.events.retain(|e| !matches!(e, egui::Event::Key { key: Key::Space, modifiers, .. } if modifiers.ctrl));
+        });
+        popup.explicit = true;
+        popup.dismissed = false;
+        ctx.data_mut(|d| d.insert_temp(popup_id(), popup.clone()));
+    }
     let escape_blurred = ctx.input(|i| i.key_pressed(Key::Escape)) && ctx.memory(|m| m.focused().is_none() && m.had_focus_last_frame(popup.editor));
     let focused = ctx.memory(|m| m.has_focus(popup.editor)) || escape_blurred;
     if popup.frame.saturating_add(1) < ctx.cumulative_frame_nr() || !focused || popup.dismissed || popup.count == 0 {
@@ -88,7 +100,6 @@ pub(crate) fn complete(ui: &mut egui::Ui, resp: &egui::Response, text: &mut Stri
     let state = egui::TextEdit::load_state(&ctx, resp.id);
     let cursor = state.as_ref().and_then(|s| s.cursor.char_range()).map(|r| r.primary.index.0).unwrap_or_else(|| text.chars().count());
     let (start, word) = word_before(text, cursor);
-    let list = suggestions(&ctx, &word);
     let previous = ctx.data(|d| d.get_temp::<Popup>(popup_id()));
     let mut popup = previous.filter(|p| p.editor == resp.id && p.word == word && p.cursor == cursor).unwrap_or(Popup {
         editor: resp.id,
@@ -96,10 +107,12 @@ pub(crate) fn complete(ui: &mut egui::Ui, resp: &egui::Response, text: &mut Stri
         word,
         cursor,
         selected: 0,
-        count: list.len(),
+        count: 0,
         accept: false,
         dismissed: false,
+        explicit: false,
     });
+    let list = suggestions_for(&ctx, &popup.word, popup.explicit);
     popup.frame = ctx.cumulative_frame_nr();
     popup.count = list.len();
     popup.selected = popup.selected.min(list.len().saturating_sub(1));
@@ -153,6 +166,7 @@ pub(crate) fn complete(ui: &mut egui::Ui, resp: &egui::Response, text: &mut Stri
 #[cfg(test)]
 mod tests {
     use super::*;
+    use crate::params_dialog::suggestions;
     use crate::{SolveApp, params_dialog};
     use serde_json::json;
 
@@ -308,6 +322,23 @@ mod tests {
         assert!(e.leaked.contains(&Key::Enter));
     }
 
+    #[test]
+    fn ctrl_space_opens_empty_expression_suggestions_and_reopens_dismissed_ones() {
+        for prefix in ["", "wi"] {
+            let mut e = Editor::new(prefix);
+            if !prefix.is_empty() {
+                e.key(Key::Escape);
+            }
+            e.frame(vec![egui::Event::Key { key: Key::Space, physical_key: None, pressed: true, repeat: false, modifiers: egui::Modifiers::CTRL }]);
+            let popup = e.ctx.data(|d| d.get_temp::<Popup>(popup_id())).unwrap();
+            assert!(popup.explicit && !popup.dismissed && popup.count > 0);
+            assert_eq!(e.text, prefix, "Ctrl+Space does not add a space");
+            e.key(Key::Tab);
+            assert!(e.accepted);
+            assert!(!e.text.is_empty());
+        }
+    }
+
     #[test]
     fn modified_navigation_remains_available_to_the_editor() {
         let mut e = Editor::new("wi");
diff --git a/crates/ui-egui/src/params_dialog.rs b/crates/ui-egui/src/params_dialog.rs
index 8752588d..23bdb450 100644
--- a/crates/ui-egui/src/params_dialog.rs
+++ b/crates/ui-egui/src/params_dialog.rs
@@ -498,16 +498,24 @@ pub(crate) fn word_before(text: &str, cursor: usize) -> (usize, String) {
 
 /// Suggestions for the word being typed.
 pub fn suggestions(ctx: &egui::Context, word: &str) -> Vec<Suggestion> {
-    if word.is_empty() || word.chars().next().is_some_and(|c| c.is_ascii_digit()) {
+    suggestions_for(ctx, word, false)
+}
+
+pub(crate) fn suggestions_for(ctx: &egui::Context, word: &str, explicit: bool) -> Vec<Suggestion> {
+    if (!explicit && word.is_empty()) || word.chars().next().is_some_and(|c| c.is_ascii_digit()) {
         return Vec::new();
     }
     let all = ctx.data(|d| d.get_temp::<Cache>(cache_id())).map(|c| c.all).unwrap_or_default();
     // A complete token is ready to submit, even when longer names share its prefix.
-    if all.iter().any(|s| s.text == word) {
+    if !explicit && all.iter().any(|s| s.text == word) {
         return Vec::new();
     }
     let w = word.to_ascii_lowercase();
-    all.iter().filter(|s| s.text.to_ascii_lowercase().starts_with(&w) && s.text.trim_end_matches('(') != word).take(8).cloned().collect()
+    all.iter()
+        .filter(|s| s.text.to_ascii_lowercase().starts_with(&w) && (explicit || s.text.trim_end_matches('(') != word))
+        .take(8)
+        .cloned()
+        .collect()
 }
 
 /// Offer keyboard and pointer completions under a focused expression box.
diff --git a/docs/book/src/guide/parameters.md b/docs/book/src/guide/parameters.md
index 5aa1f18a..c3edf3ea 100644
--- a/docs/book/src/guide/parameters.md
+++ b/docs/book/src/guide/parameters.md
@@ -11,7 +11,9 @@ parameter editor. The separate **Configurations** button opens the configuration
 
 Press **Enter** in the new parameter's name, expression or comment field to add it.
 Valid entries return focus to the name field for the next parameter; invalid entries remain
-editable. In expression fields, **Up/Down** selects an autocomplete suggestion,
+editable. In expression fields, type a parameter or dimension name for autocomplete,
+or press **Ctrl+Space** to open suggestions, including in an empty field.
+**Up/Down** selects an autocomplete suggestion,
 **Enter/Tab** accepts it, and **Escape** dismisses the suggestions. Accepting a suggestion
 does not also submit the parameter.